* [PATCH rdma-next 08/50] RDMA/core: Reject zero CQE count
From: Leon Romanovsky @ 2026-02-13 10:57 UTC (permalink / raw)
To: Jason Gunthorpe, Leon Romanovsky, Selvin Xavier, Kalesh AP,
Potnuri Bharat Teja, Michael Margolin, Gal Pressman,
Yossi Leybovich, Cheng Xu, Kai Shen, Chengchang Tang,
Junxian Huang, Abhijit Gangurde, Allen Hubbe, Krzysztof Czurylo,
Tatyana Nikolova, Long Li, Konstantin Taranov, Yishai Hadas,
Michal Kalderon, Bryan Tan, Vishnu Dasa,
Broadcom internal kernel review list, Christian Benvenuti,
Nelson Escobar, Dennis Dalessandro, Bernard Metzler, Zhu Yanjun
Cc: linux-kernel, linux-rdma, linux-hyperv
In-Reply-To: <20260213-refactor-umem-v1-0-f3be85847922@nvidia.com>
From: Leon Romanovsky <leonro@nvidia.com>
All drivers already ensure that the number of CQEs is at least 1.
Add this validation to the core so drivers no longer need to repeat it.
Future patches converting to the .create_user_cq() interface will remove
the per‑driver checks.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
drivers/infiniband/core/cq.c | 3 +++
drivers/infiniband/core/uverbs_cmd.c | 3 +++
drivers/infiniband/core/uverbs_std_types_cq.c | 15 +++++++++------
drivers/infiniband/core/verbs.c | 3 +++
4 files changed, 18 insertions(+), 6 deletions(-)
diff --git a/drivers/infiniband/core/cq.c b/drivers/infiniband/core/cq.c
index 584537c71545..7e0b54ec4141 100644
--- a/drivers/infiniband/core/cq.c
+++ b/drivers/infiniband/core/cq.c
@@ -220,6 +220,9 @@ struct ib_cq *__ib_alloc_cq(struct ib_device *dev, void *private, int nr_cqe,
struct ib_cq *cq;
int ret = -ENOMEM;
+ if (WARN_ON_ONCE(!nr_cqe))
+ return ERR_PTR(-EINVAL);
+
cq = rdma_zalloc_drv_obj(dev, ib_cq);
if (!cq)
return ERR_PTR(ret);
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index c7be592f60e8..041bed7a43b4 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -1032,6 +1032,9 @@ static int create_cq(struct uverbs_attr_bundle *attrs,
if (cmd->comp_vector >= attrs->ufile->device->num_comp_vectors)
return -EINVAL;
+ if (!cmd->cqe)
+ return -EINVAL;
+
obj = (struct ib_ucq_object *)uobj_alloc(UVERBS_OBJECT_CQ, attrs,
&ib_dev);
if (IS_ERR(obj))
diff --git a/drivers/infiniband/core/uverbs_std_types_cq.c b/drivers/infiniband/core/uverbs_std_types_cq.c
index b999d8d62694..d2c8f71f934c 100644
--- a/drivers/infiniband/core/uverbs_std_types_cq.c
+++ b/drivers/infiniband/core/uverbs_std_types_cq.c
@@ -84,12 +84,15 @@ static int UVERBS_HANDLER(UVERBS_METHOD_CQ_CREATE)(
ret = uverbs_copy_from(&attr.comp_vector, attrs,
UVERBS_ATTR_CREATE_CQ_COMP_VECTOR);
- if (!ret)
- ret = uverbs_copy_from(&attr.cqe, attrs,
- UVERBS_ATTR_CREATE_CQ_CQE);
- if (!ret)
- ret = uverbs_copy_from(&user_handle, attrs,
- UVERBS_ATTR_CREATE_CQ_USER_HANDLE);
+ if (ret)
+ return ret;
+
+ ret = uverbs_copy_from(&attr.cqe, attrs, UVERBS_ATTR_CREATE_CQ_CQE);
+ if (ret || !attr.cqe)
+ return ret ? : -EINVAL;
+
+ ret = uverbs_copy_from(&user_handle, attrs,
+ UVERBS_ATTR_CREATE_CQ_USER_HANDLE);
if (ret)
return ret;
diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
index d0880346ebe2..9d075eeda463 100644
--- a/drivers/infiniband/core/verbs.c
+++ b/drivers/infiniband/core/verbs.c
@@ -2203,6 +2203,9 @@ struct ib_cq *__ib_create_cq(struct ib_device *device,
if (!cq)
return ERR_PTR(-ENOMEM);
+ if (WARN_ON_ONCE(!cq_attr->cqe))
+ return ERR_PTR(-EINVAL);
+
cq->device = device;
cq->comp_handler = comp_handler;
cq->event_handler = event_handler;
--
2.52.0
^ permalink raw reply related
* [PATCH rdma-next 07/50] RDMA/core: Prepare create CQ path for API unification
From: Leon Romanovsky @ 2026-02-13 10:57 UTC (permalink / raw)
To: Jason Gunthorpe, Leon Romanovsky, Selvin Xavier, Kalesh AP,
Potnuri Bharat Teja, Michael Margolin, Gal Pressman,
Yossi Leybovich, Cheng Xu, Kai Shen, Chengchang Tang,
Junxian Huang, Abhijit Gangurde, Allen Hubbe, Krzysztof Czurylo,
Tatyana Nikolova, Long Li, Konstantin Taranov, Yishai Hadas,
Michal Kalderon, Bryan Tan, Vishnu Dasa,
Broadcom internal kernel review list, Christian Benvenuti,
Nelson Escobar, Dennis Dalessandro, Bernard Metzler, Zhu Yanjun
Cc: linux-kernel, linux-rdma, linux-hyperv
In-Reply-To: <20260213-refactor-umem-v1-0-f3be85847922@nvidia.com>
From: Leon Romanovsky <leonro@nvidia.com>
Ensure that .create_cq_umem() and .create_cq() follow the same API
contract, allowing drivers to be gradually migrated to the umem-aware
CQ management flow.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
drivers/infiniband/core/device.c | 2 +-
drivers/infiniband/core/uverbs_cmd.c | 5 ++++-
drivers/infiniband/core/uverbs_std_types_cq.c | 16 +++++++++++-----
drivers/infiniband/core/verbs.c | 6 +++++-
drivers/infiniband/hw/efa/efa.h | 6 ++----
drivers/infiniband/hw/efa/efa_main.c | 3 +--
drivers/infiniband/hw/efa/efa_verbs.c | 10 ++--------
include/rdma/ib_verbs.h | 3 +--
8 files changed, 27 insertions(+), 24 deletions(-)
diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index 4e09f6e0995e..9209b8c664ef 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -2701,7 +2701,7 @@ void ib_set_device_ops(struct ib_device *dev, const struct ib_device_ops *ops)
SET_DEVICE_OP(dev_ops, create_ah);
SET_DEVICE_OP(dev_ops, create_counters);
SET_DEVICE_OP(dev_ops, create_cq);
- SET_DEVICE_OP(dev_ops, create_cq_umem);
+ SET_DEVICE_OP(dev_ops, create_user_cq);
SET_DEVICE_OP(dev_ops, create_flow);
SET_DEVICE_OP(dev_ops, create_qp);
SET_DEVICE_OP(dev_ops, create_rwq_ind_table);
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index fb19395b9f2a..c7be592f60e8 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -1068,7 +1068,10 @@ static int create_cq(struct uverbs_attr_bundle *attrs,
rdma_restrack_new(&cq->res, RDMA_RESTRACK_CQ);
rdma_restrack_set_name(&cq->res, NULL);
- ret = ib_dev->ops.create_cq(cq, &attr, attrs);
+ if (ib_dev->ops.create_user_cq)
+ ret = ib_dev->ops.create_user_cq(cq, &attr, attrs);
+ else
+ ret = ib_dev->ops.create_cq(cq, &attr, attrs);
if (ret)
goto err_free;
rdma_restrack_add(&cq->res);
diff --git a/drivers/infiniband/core/uverbs_std_types_cq.c b/drivers/infiniband/core/uverbs_std_types_cq.c
index 05809f9ff0f6..b999d8d62694 100644
--- a/drivers/infiniband/core/uverbs_std_types_cq.c
+++ b/drivers/infiniband/core/uverbs_std_types_cq.c
@@ -78,7 +78,8 @@ static int UVERBS_HANDLER(UVERBS_METHOD_CQ_CREATE)(
int buffer_fd;
int ret;
- if ((!ib_dev->ops.create_cq && !ib_dev->ops.create_cq_umem) || !ib_dev->ops.destroy_cq)
+ if ((!ib_dev->ops.create_cq && !ib_dev->ops.create_user_cq) ||
+ !ib_dev->ops.destroy_cq)
return -EOPNOTSUPP;
ret = uverbs_copy_from(&attr.comp_vector, attrs,
@@ -130,7 +131,7 @@ static int UVERBS_HANDLER(UVERBS_METHOD_CQ_CREATE)(
if (uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_FD) ||
uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_OFFSET) ||
- !ib_dev->ops.create_cq_umem) {
+ !ib_dev->ops.create_user_cq) {
ret = -EINVAL;
goto err_event_file;
}
@@ -155,7 +156,7 @@ static int UVERBS_HANDLER(UVERBS_METHOD_CQ_CREATE)(
goto err_event_file;
if (uverbs_attr_is_valid(attrs, UVERBS_ATTR_CREATE_CQ_BUFFER_VA) ||
- !ib_dev->ops.create_cq_umem) {
+ !ib_dev->ops.create_user_cq) {
ret = -EINVAL;
goto err_event_file;
}
@@ -196,11 +197,16 @@ static int UVERBS_HANDLER(UVERBS_METHOD_CQ_CREATE)(
rdma_restrack_new(&cq->res, RDMA_RESTRACK_CQ);
rdma_restrack_set_name(&cq->res, NULL);
- ret = umem ? ib_dev->ops.create_cq_umem(cq, &attr, umem, attrs) :
- ib_dev->ops.create_cq(cq, &attr, attrs);
+ if (ib_dev->ops.create_user_cq)
+ ret = ib_dev->ops.create_user_cq(cq, &attr, attrs);
+ else
+ ret = ib_dev->ops.create_cq(cq, &attr, attrs);
if (ret)
goto err_free;
+ /* Check that driver didn't overrun existing umem */
+ WARN_ON(umem && cq->umem != umem);
+
obj->uevent.uobject.object = cq;
obj->uevent.uobject.user_handle = user_handle;
rdma_restrack_add(&cq->res);
diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
index ad48d2458a3f..d0880346ebe2 100644
--- a/drivers/infiniband/core/verbs.c
+++ b/drivers/infiniband/core/verbs.c
@@ -2204,7 +2204,6 @@ struct ib_cq *__ib_create_cq(struct ib_device *device,
return ERR_PTR(-ENOMEM);
cq->device = device;
- cq->uobject = NULL;
cq->comp_handler = comp_handler;
cq->event_handler = event_handler;
cq->cq_context = cq_context;
@@ -2219,6 +2218,11 @@ struct ib_cq *__ib_create_cq(struct ib_device *device,
kfree(cq);
return ERR_PTR(ret);
}
+ /*
+ * We are in kernel verbs flow and drivers are not allowed
+ * to set umem pointer, it needs to stay NULL.
+ */
+ WARN_ON_ONCE(cq->umem);
rdma_restrack_add(&cq->res);
return cq;
diff --git a/drivers/infiniband/hw/efa/efa.h b/drivers/infiniband/hw/efa/efa.h
index 96f9c3bc98b2..00b19f2ba3da 100644
--- a/drivers/infiniband/hw/efa/efa.h
+++ b/drivers/infiniband/hw/efa/efa.h
@@ -161,10 +161,8 @@ int efa_destroy_qp(struct ib_qp *ibqp, struct ib_udata *udata);
int efa_create_qp(struct ib_qp *ibqp, struct ib_qp_init_attr *init_attr,
struct ib_udata *udata);
int efa_destroy_cq(struct ib_cq *ibcq, struct ib_udata *udata);
-int efa_create_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
- struct uverbs_attr_bundle *attrs);
-int efa_create_cq_umem(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
- struct ib_umem *umem, struct uverbs_attr_bundle *attrs);
+int efa_create_user_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
+ struct uverbs_attr_bundle *attrs);
struct ib_mr *efa_reg_mr(struct ib_pd *ibpd, u64 start, u64 length,
u64 virt_addr, int access_flags,
struct ib_dmah *dmah,
diff --git a/drivers/infiniband/hw/efa/efa_main.c b/drivers/infiniband/hw/efa/efa_main.c
index 6c415b9adb5f..a1d68dc49e45 100644
--- a/drivers/infiniband/hw/efa/efa_main.c
+++ b/drivers/infiniband/hw/efa/efa_main.c
@@ -371,8 +371,7 @@ static const struct ib_device_ops efa_dev_ops = {
.alloc_hw_device_stats = efa_alloc_hw_device_stats,
.alloc_pd = efa_alloc_pd,
.alloc_ucontext = efa_alloc_ucontext,
- .create_cq = efa_create_cq,
- .create_cq_umem = efa_create_cq_umem,
+ .create_user_cq = efa_create_user_cq,
.create_qp = efa_create_qp,
.create_user_ah = efa_create_ah,
.dealloc_pd = efa_dealloc_pd,
diff --git a/drivers/infiniband/hw/efa/efa_verbs.c b/drivers/infiniband/hw/efa/efa_verbs.c
index bc69aef3e436..d465e6acfe3c 100644
--- a/drivers/infiniband/hw/efa/efa_verbs.c
+++ b/drivers/infiniband/hw/efa/efa_verbs.c
@@ -1130,8 +1130,8 @@ static int cq_mmap_entries_setup(struct efa_dev *dev, struct efa_cq *cq,
return 0;
}
-int efa_create_cq_umem(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
- struct ib_umem *umem, struct uverbs_attr_bundle *attrs)
+int efa_create_user_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
+ struct uverbs_attr_bundle *attrs)
{
struct ib_udata *udata = &attrs->driver_udata;
struct efa_ucontext *ucontext = rdma_udata_to_drv_context(
@@ -1306,12 +1306,6 @@ int efa_create_cq_umem(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
return err;
}
-int efa_create_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
- struct uverbs_attr_bundle *attrs)
-{
- return efa_create_cq_umem(ibcq, attr, NULL, attrs);
-}
-
static int umem_to_page_list(struct efa_dev *dev,
struct ib_umem *umem,
u64 *page_list,
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index b1e34fd2ed5f..67aa5fc2c0b7 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2529,9 +2529,8 @@ struct ib_device_ops {
int (*destroy_qp)(struct ib_qp *qp, struct ib_udata *udata);
int (*create_cq)(struct ib_cq *cq, const struct ib_cq_init_attr *attr,
struct uverbs_attr_bundle *attrs);
- int (*create_cq_umem)(struct ib_cq *cq,
+ int (*create_user_cq)(struct ib_cq *cq,
const struct ib_cq_init_attr *attr,
- struct ib_umem *umem,
struct uverbs_attr_bundle *attrs);
int (*modify_cq)(struct ib_cq *cq, u16 cq_count, u16 cq_period);
int (*destroy_cq)(struct ib_cq *cq, struct ib_udata *udata);
--
2.52.0
^ permalink raw reply related
* [PATCH rdma-next 02/50] RDMA/umem: Allow including ib_umem header from any location
From: Leon Romanovsky @ 2026-02-13 10:57 UTC (permalink / raw)
To: Jason Gunthorpe, Leon Romanovsky, Selvin Xavier, Kalesh AP,
Potnuri Bharat Teja, Michael Margolin, Gal Pressman,
Yossi Leybovich, Cheng Xu, Kai Shen, Chengchang Tang,
Junxian Huang, Abhijit Gangurde, Allen Hubbe, Krzysztof Czurylo,
Tatyana Nikolova, Long Li, Konstantin Taranov, Yishai Hadas,
Michal Kalderon, Bryan Tan, Vishnu Dasa,
Broadcom internal kernel review list, Christian Benvenuti,
Nelson Escobar, Dennis Dalessandro, Bernard Metzler, Zhu Yanjun
Cc: linux-kernel, linux-rdma, linux-hyperv
In-Reply-To: <20260213-refactor-umem-v1-0-f3be85847922@nvidia.com>
From: Leon Romanovsky <leonro@nvidia.com>
Including ib_umem.h currently triggers circular dependency errors.
These issues can be resolved by removing the include of ib_verbs.h,
which was only needed to resolve the struct ib_device pointer.
>> depmod: ERROR: Cycle detected: ib_core -> ib_uverbs -> ib_core
>> depmod: ERROR: Found 2 modules in dependency cycles!
make[3]: *** [scripts/Makefile.modinst:132: depmod] Error 1
make[3]: Target '__modinst' not remade because of errors.
make[2]: *** [Makefile:1960: modules_install] Error 2
make[1]: *** [Makefile:248: __sub-make] Error 2
make[1]: Target 'modules_install' not remade because of errors.
make: *** [Makefile:248: __sub-make] Error 2
make: Target 'modules_install' not remade because of errors.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
include/rdma/ib_umem.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index ce47688dd003..084a1d9a66f3 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -10,8 +10,8 @@
#include <linux/list.h>
#include <linux/scatterlist.h>
#include <linux/workqueue.h>
-#include <rdma/ib_verbs.h>
+struct ib_device;
struct ib_ucontext;
struct ib_umem_odp;
struct dma_buf_attach_ops;
--
2.52.0
^ permalink raw reply related
* [PATCH rdma-next 05/50] RDMA/core: Manage CQ umem in core code
From: Leon Romanovsky @ 2026-02-13 10:57 UTC (permalink / raw)
To: Jason Gunthorpe, Leon Romanovsky, Selvin Xavier, Kalesh AP,
Potnuri Bharat Teja, Michael Margolin, Gal Pressman,
Yossi Leybovich, Cheng Xu, Kai Shen, Chengchang Tang,
Junxian Huang, Abhijit Gangurde, Allen Hubbe, Krzysztof Czurylo,
Tatyana Nikolova, Long Li, Konstantin Taranov, Yishai Hadas,
Michal Kalderon, Bryan Tan, Vishnu Dasa,
Broadcom internal kernel review list, Christian Benvenuti,
Nelson Escobar, Dennis Dalessandro, Bernard Metzler, Zhu Yanjun
Cc: linux-kernel, linux-rdma, linux-hyperv
In-Reply-To: <20260213-refactor-umem-v1-0-f3be85847922@nvidia.com>
From: Leon Romanovsky <leonro@nvidia.com>
In the current implementation, CQ umem is handled both by ib_core and
the driver. ib_core sometimes creates and destroys it, while the driver
also destroys it.
Store the umem in struct ib_cq and ensure that only ib_core manages
its lifetime, relying solely on its internal reference counter.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
drivers/infiniband/core/umem.c | 2 +-
drivers/infiniband/core/uverbs_cmd.c | 1 +
drivers/infiniband/core/uverbs_std_types_cq.c | 7 ++++++-
drivers/infiniband/core/verbs.c | 2 ++
drivers/infiniband/hw/efa/efa_verbs.c | 24 +++++++++++-------------
include/rdma/ib_verbs.h | 1 +
6 files changed, 22 insertions(+), 15 deletions(-)
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 8137031c2a65..fc70b918f3f0 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -283,7 +283,7 @@ EXPORT_SYMBOL(ib_umem_get);
*/
void ib_umem_release(struct ib_umem *umem)
{
- if (!umem)
+ if (IS_ERR_OR_NULL(umem))
return;
if (umem->is_dmabuf)
return ib_umem_dmabuf_release(to_ib_umem_dmabuf(umem));
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index f4616deeca54..fb19395b9f2a 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -1085,6 +1085,7 @@ static int create_cq(struct uverbs_attr_bundle *attrs,
return uverbs_response(attrs, &resp, sizeof(resp));
err_free:
+ ib_umem_release(cq->umem);
rdma_restrack_put(&cq->res);
kfree(cq);
err_file:
diff --git a/drivers/infiniband/core/uverbs_std_types_cq.c b/drivers/infiniband/core/uverbs_std_types_cq.c
index fab5d914029d..05809f9ff0f6 100644
--- a/drivers/infiniband/core/uverbs_std_types_cq.c
+++ b/drivers/infiniband/core/uverbs_std_types_cq.c
@@ -186,6 +186,11 @@ static int UVERBS_HANDLER(UVERBS_METHOD_CQ_CREATE)(
cq->comp_handler = ib_uverbs_comp_handler;
cq->event_handler = ib_uverbs_cq_event_handler;
cq->cq_context = ev_file ? &ev_file->ev_queue : NULL;
+ /*
+ * If UMEM is not provided here, legacy drivers will set it during
+ * CQ creation based on their internal udata.
+ */
+ cq->umem = umem;
atomic_set(&cq->usecnt, 0);
rdma_restrack_new(&cq->res, RDMA_RESTRACK_CQ);
@@ -206,7 +211,7 @@ static int UVERBS_HANDLER(UVERBS_METHOD_CQ_CREATE)(
return ret;
err_free:
- ib_umem_release(umem);
+ ib_umem_release(cq->umem);
rdma_restrack_put(&cq->res);
kfree(cq);
err_event_file:
diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
index 47a97797d7be..ad48d2458a3f 100644
--- a/drivers/infiniband/core/verbs.c
+++ b/drivers/infiniband/core/verbs.c
@@ -49,6 +49,7 @@
#include <rdma/ib_verbs.h>
#include <rdma/ib_cache.h>
#include <rdma/ib_addr.h>
+#include <rdma/ib_umem.h>
#include <rdma/rw.h>
#include <rdma/lag.h>
@@ -2249,6 +2250,7 @@ int ib_destroy_cq_user(struct ib_cq *cq, struct ib_udata *udata)
if (ret)
return ret;
+ ib_umem_release(cq->umem);
rdma_restrack_del(&cq->res);
kfree(cq);
return ret;
diff --git a/drivers/infiniband/hw/efa/efa_verbs.c b/drivers/infiniband/hw/efa/efa_verbs.c
index 19e3033d4ff7..ae9b98b4b528 100644
--- a/drivers/infiniband/hw/efa/efa_verbs.c
+++ b/drivers/infiniband/hw/efa/efa_verbs.c
@@ -1083,15 +1083,14 @@ int efa_destroy_cq(struct ib_cq *ibcq, struct ib_udata *udata)
cq->cq_idx, cq->cpu_addr, cq->size, &cq->dma_addr);
efa_destroy_cq_idx(dev, cq->cq_idx);
- efa_cq_user_mmap_entries_remove(cq);
+ if (cq->cpu_addr)
+ efa_cq_user_mmap_entries_remove(cq);
if (cq->eq) {
xa_erase(&dev->cqs_xa, cq->cq_idx);
synchronize_irq(cq->eq->irq.irqn);
}
- if (cq->umem)
- ib_umem_release(cq->umem);
- else
+ if (cq->cpu_addr)
efa_free_mapped(dev, cq->cpu_addr, cq->dma_addr, cq->size, DMA_FROM_DEVICE);
return 0;
}
@@ -1212,22 +1211,20 @@ int efa_create_cq_umem(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
cq->ucontext = ucontext;
cq->size = PAGE_ALIGN(cmd.cq_entry_size * entries * cmd.num_sub_cqs);
- if (umem) {
- if (umem->length < cq->size) {
+ if (ibcq->umem) {
+ if (ibcq->umem->length < cq->size) {
ibdev_dbg(&dev->ibdev, "External memory too small\n");
err = -EINVAL;
goto err_out;
}
- if (!ib_umem_is_contiguous(umem)) {
+ if (!ib_umem_is_contiguous(ibcq->umem)) {
ibdev_dbg(&dev->ibdev, "Non contiguous CQ unsupported\n");
err = -EINVAL;
goto err_out;
}
- cq->cpu_addr = NULL;
- cq->dma_addr = ib_umem_start_dma_addr(umem);
- cq->umem = umem;
+ cq->dma_addr = ib_umem_start_dma_addr(ibcq->umem);
} else {
cq->cpu_addr = efa_zalloc_mapped(dev, &cq->dma_addr, cq->size,
DMA_FROM_DEVICE);
@@ -1259,7 +1256,7 @@ int efa_create_cq_umem(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
cq->ibcq.cqe = result.actual_depth;
WARN_ON_ONCE(entries != result.actual_depth);
- if (!umem)
+ if (cq->cpu_addr)
err = cq_mmap_entries_setup(dev, cq, &resp, result.db_valid);
if (err) {
@@ -1296,11 +1293,12 @@ int efa_create_cq_umem(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
if (cq->eq)
xa_erase(&dev->cqs_xa, cq->cq_idx);
err_remove_mmap:
- efa_cq_user_mmap_entries_remove(cq);
+ if (cq->cpu_addr)
+ efa_cq_user_mmap_entries_remove(cq);
err_destroy_cq:
efa_destroy_cq_idx(dev, cq->cq_idx);
err_free_mapped:
- if (!umem)
+ if (cq->cpu_addr)
efa_free_mapped(dev, cq->cpu_addr, cq->dma_addr, cq->size,
DMA_FROM_DEVICE);
err_out:
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index e1ec5a6c74e6..b1e34fd2ed5f 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -1649,6 +1649,7 @@ struct ib_cq {
u8 interrupt:1;
u8 shared:1;
unsigned int comp_vector;
+ struct ib_umem *umem;
/*
* Implementation details of the RDMA core, don't use in drivers:
--
2.52.0
^ permalink raw reply related
* [PATCH rdma-next 04/50] RDMA/core: Promote UMEM to a core component
From: Leon Romanovsky @ 2026-02-13 10:57 UTC (permalink / raw)
To: Jason Gunthorpe, Leon Romanovsky, Selvin Xavier, Kalesh AP,
Potnuri Bharat Teja, Michael Margolin, Gal Pressman,
Yossi Leybovich, Cheng Xu, Kai Shen, Chengchang Tang,
Junxian Huang, Abhijit Gangurde, Allen Hubbe, Krzysztof Czurylo,
Tatyana Nikolova, Long Li, Konstantin Taranov, Yishai Hadas,
Michal Kalderon, Bryan Tan, Vishnu Dasa,
Broadcom internal kernel review list, Christian Benvenuti,
Nelson Escobar, Dennis Dalessandro, Bernard Metzler, Zhu Yanjun
Cc: linux-kernel, linux-rdma, linux-hyperv
In-Reply-To: <20260213-refactor-umem-v1-0-f3be85847922@nvidia.com>
From: Leon Romanovsky <leonro@nvidia.com>
To manage UMEM objects at the core level and reuse the existing
ib_destroy_cq*() flow, move the UMEM files to be built together with
ib_core. Attempting to call ib_umem_release() from verbs.c currently
results in the following error:
depmod: ERROR: Cycle detected: ib_core -> ib_uverbs -> ib_core
depmod: ERROR: Found 2 modules in dependency cycles!
verbs.c:(.text+0x250c): undefined reference to `ib_umem_release'
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
drivers/infiniband/core/Makefile | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/infiniband/core/Makefile b/drivers/infiniband/core/Makefile
index 48922e0ede56..ada9877d02df 100644
--- a/drivers/infiniband/core/Makefile
+++ b/drivers/infiniband/core/Makefile
@@ -16,6 +16,8 @@ ib_core-y := packer.o ud_header.o verbs.o cq.o rw.o sysfs.o \
ib_core-$(CONFIG_SECURITY_INFINIBAND) += security.o
ib_core-$(CONFIG_CGROUP_RDMA) += cgroup.o
+ib_core-$(CONFIG_INFINIBAND_USER_MEM) += umem.o umem_dmabuf.o
+ib_core-$(CONFIG_INFINIBAND_ON_DEMAND_PAGING) += umem_odp.o
ib_cm-y := cm.o cm_trace.o
@@ -42,5 +44,3 @@ ib_uverbs-y := uverbs_main.o uverbs_cmd.o uverbs_marshall.o \
uverbs_std_types_wq.o \
uverbs_std_types_qp.o \
ucaps.o
-ib_uverbs-$(CONFIG_INFINIBAND_USER_MEM) += umem.o umem_dmabuf.o
-ib_uverbs-$(CONFIG_INFINIBAND_ON_DEMAND_PAGING) += umem_odp.o
--
2.52.0
^ permalink raw reply related
* [PATCH rdma-next 03/50] RDMA/umem: Remove unnecessary includes and defines from ib_umem header
From: Leon Romanovsky @ 2026-02-13 10:57 UTC (permalink / raw)
To: Jason Gunthorpe, Leon Romanovsky, Selvin Xavier, Kalesh AP,
Potnuri Bharat Teja, Michael Margolin, Gal Pressman,
Yossi Leybovich, Cheng Xu, Kai Shen, Chengchang Tang,
Junxian Huang, Abhijit Gangurde, Allen Hubbe, Krzysztof Czurylo,
Tatyana Nikolova, Long Li, Konstantin Taranov, Yishai Hadas,
Michal Kalderon, Bryan Tan, Vishnu Dasa,
Broadcom internal kernel review list, Christian Benvenuti,
Nelson Escobar, Dennis Dalessandro, Bernard Metzler, Zhu Yanjun
Cc: linux-kernel, linux-rdma, linux-hyperv
In-Reply-To: <20260213-refactor-umem-v1-0-f3be85847922@nvidia.com>
From: Leon Romanovsky <leonro@nvidia.com>
The ib_umem header no longer requires the removed includes or forward
declarations, so drop them to reduce clutter.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
include/rdma/ib_umem.h | 4 ----
1 file changed, 4 deletions(-)
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index 084a1d9a66f3..c3ab11e6879f 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -7,13 +7,9 @@
#ifndef IB_UMEM_H
#define IB_UMEM_H
-#include <linux/list.h>
#include <linux/scatterlist.h>
-#include <linux/workqueue.h>
struct ib_device;
-struct ib_ucontext;
-struct ib_umem_odp;
struct dma_buf_attach_ops;
struct ib_umem {
--
2.52.0
^ permalink raw reply related
* [PATCH rdma-next 01/50] RDMA: Move DMA block iterator logic into dedicated files
From: Leon Romanovsky @ 2026-02-13 10:57 UTC (permalink / raw)
To: Jason Gunthorpe, Leon Romanovsky, Selvin Xavier, Kalesh AP,
Potnuri Bharat Teja, Michael Margolin, Gal Pressman,
Yossi Leybovich, Cheng Xu, Kai Shen, Chengchang Tang,
Junxian Huang, Abhijit Gangurde, Allen Hubbe, Krzysztof Czurylo,
Tatyana Nikolova, Long Li, Konstantin Taranov, Yishai Hadas,
Michal Kalderon, Bryan Tan, Vishnu Dasa,
Broadcom internal kernel review list, Christian Benvenuti,
Nelson Escobar, Dennis Dalessandro, Bernard Metzler, Zhu Yanjun
Cc: linux-kernel, linux-rdma, linux-hyperv
In-Reply-To: <20260213-refactor-umem-v1-0-f3be85847922@nvidia.com>
From: Leon Romanovsky <leonro@nvidia.com>
The DMA iterator logic was mixed into verbs and umem-specific code,
forcing all users to include rdma/ib_umem.h. Move the block iterator
logic into iter.c and rdma/iter.h so that rdma/ib_umem.h and
rdma/ib_verbs.h can be separated in a follow-up patch.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
drivers/infiniband/core/Makefile | 2 +-
drivers/infiniband/core/iter.c | 43 ++++++++++++++
drivers/infiniband/core/verbs.c | 38 ------------
drivers/infiniband/hw/bnxt_re/qplib_res.c | 2 +-
drivers/infiniband/hw/cxgb4/mem.c | 2 +-
drivers/infiniband/hw/efa/efa_verbs.c | 2 +-
drivers/infiniband/hw/erdma/erdma_verbs.c | 2 +-
drivers/infiniband/hw/hns/hns_roce_alloc.c | 2 +-
drivers/infiniband/hw/ionic/ionic_ibdev.h | 2 +-
drivers/infiniband/hw/irdma/main.h | 2 +-
drivers/infiniband/hw/mana/mana_ib.h | 2 +-
drivers/infiniband/hw/mlx4/mr.c | 1 +
drivers/infiniband/hw/mlx5/mem.c | 1 +
drivers/infiniband/hw/mlx5/umr.c | 1 +
drivers/infiniband/hw/mthca/mthca_provider.c | 2 +-
drivers/infiniband/hw/ocrdma/ocrdma_verbs.c | 2 +-
drivers/infiniband/hw/qedr/verbs.c | 2 +-
drivers/infiniband/hw/vmw_pvrdma/pvrdma.h | 2 +-
include/rdma/ib_umem.h | 30 ----------
include/rdma/ib_verbs.h | 48 ---------------
include/rdma/iter.h | 88 ++++++++++++++++++++++++++++
21 files changed, 147 insertions(+), 129 deletions(-)
diff --git a/drivers/infiniband/core/Makefile b/drivers/infiniband/core/Makefile
index f483e0c12444..48922e0ede56 100644
--- a/drivers/infiniband/core/Makefile
+++ b/drivers/infiniband/core/Makefile
@@ -12,7 +12,7 @@ ib_core-y := packer.o ud_header.o verbs.o cq.o rw.o sysfs.o \
roce_gid_mgmt.o mr_pool.o addr.o sa_query.o \
multicast.o mad.o smi.o agent.o mad_rmpp.o \
nldev.o restrack.o counters.o ib_core_uverbs.o \
- trace.o lag.o
+ trace.o lag.o iter.o
ib_core-$(CONFIG_SECURITY_INFINIBAND) += security.o
ib_core-$(CONFIG_CGROUP_RDMA) += cgroup.o
diff --git a/drivers/infiniband/core/iter.c b/drivers/infiniband/core/iter.c
new file mode 100644
index 000000000000..8e543d100657
--- /dev/null
+++ b/drivers/infiniband/core/iter.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+/* Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. */
+
+#include <linux/export.h>
+#include <rdma/iter.h>
+
+void __rdma_block_iter_start(struct ib_block_iter *biter,
+ struct scatterlist *sglist, unsigned int nents,
+ unsigned long pgsz)
+{
+ memset(biter, 0, sizeof(struct ib_block_iter));
+ biter->__sg = sglist;
+ biter->__sg_nents = nents;
+
+ /* Driver provides best block size to use */
+ biter->__pg_bit = __fls(pgsz);
+}
+EXPORT_SYMBOL(__rdma_block_iter_start);
+
+bool __rdma_block_iter_next(struct ib_block_iter *biter)
+{
+ unsigned int block_offset;
+ unsigned int delta;
+
+ if (!biter->__sg_nents || !biter->__sg)
+ return false;
+
+ biter->__dma_addr = sg_dma_address(biter->__sg) + biter->__sg_advance;
+ block_offset = biter->__dma_addr & (BIT_ULL(biter->__pg_bit) - 1);
+ delta = BIT_ULL(biter->__pg_bit) - block_offset;
+
+ while (biter->__sg_nents && biter->__sg &&
+ sg_dma_len(biter->__sg) - biter->__sg_advance <= delta) {
+ delta -= sg_dma_len(biter->__sg) - biter->__sg_advance;
+ biter->__sg_advance = 0;
+ biter->__sg = sg_next(biter->__sg);
+ biter->__sg_nents--;
+ }
+ biter->__sg_advance += delta;
+
+ return true;
+}
+EXPORT_SYMBOL(__rdma_block_iter_next);
diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
index 02ebc3e52196..47a97797d7be 100644
--- a/drivers/infiniband/core/verbs.c
+++ b/drivers/infiniband/core/verbs.c
@@ -3154,44 +3154,6 @@ int rdma_init_netdev(struct ib_device *device, u32 port_num,
}
EXPORT_SYMBOL(rdma_init_netdev);
-void __rdma_block_iter_start(struct ib_block_iter *biter,
- struct scatterlist *sglist, unsigned int nents,
- unsigned long pgsz)
-{
- memset(biter, 0, sizeof(struct ib_block_iter));
- biter->__sg = sglist;
- biter->__sg_nents = nents;
-
- /* Driver provides best block size to use */
- biter->__pg_bit = __fls(pgsz);
-}
-EXPORT_SYMBOL(__rdma_block_iter_start);
-
-bool __rdma_block_iter_next(struct ib_block_iter *biter)
-{
- unsigned int block_offset;
- unsigned int delta;
-
- if (!biter->__sg_nents || !biter->__sg)
- return false;
-
- biter->__dma_addr = sg_dma_address(biter->__sg) + biter->__sg_advance;
- block_offset = biter->__dma_addr & (BIT_ULL(biter->__pg_bit) - 1);
- delta = BIT_ULL(biter->__pg_bit) - block_offset;
-
- while (biter->__sg_nents && biter->__sg &&
- sg_dma_len(biter->__sg) - biter->__sg_advance <= delta) {
- delta -= sg_dma_len(biter->__sg) - biter->__sg_advance;
- biter->__sg_advance = 0;
- biter->__sg = sg_next(biter->__sg);
- biter->__sg_nents--;
- }
- biter->__sg_advance += delta;
-
- return true;
-}
-EXPORT_SYMBOL(__rdma_block_iter_next);
-
/**
* rdma_alloc_hw_stats_struct - Helper function to allocate dynamic struct
* for the drivers.
diff --git a/drivers/infiniband/hw/bnxt_re/qplib_res.c b/drivers/infiniband/hw/bnxt_re/qplib_res.c
index 875d7b52c06a..64b02ea98cac 100644
--- a/drivers/infiniband/hw/bnxt_re/qplib_res.c
+++ b/drivers/infiniband/hw/bnxt_re/qplib_res.c
@@ -46,7 +46,7 @@
#include <linux/if_vlan.h>
#include <linux/vmalloc.h>
#include <rdma/ib_verbs.h>
-#include <rdma/ib_umem.h>
+#include <rdma/iter.h>
#include "roce_hsi.h"
#include "qplib_res.h"
diff --git a/drivers/infiniband/hw/cxgb4/mem.c b/drivers/infiniband/hw/cxgb4/mem.c
index adeed7447e7b..e0ec2c4158a0 100644
--- a/drivers/infiniband/hw/cxgb4/mem.c
+++ b/drivers/infiniband/hw/cxgb4/mem.c
@@ -32,9 +32,9 @@
#include <linux/module.h>
#include <linux/moduleparam.h>
-#include <rdma/ib_umem.h>
#include <linux/atomic.h>
#include <rdma/ib_user_verbs.h>
+#include <rdma/iter.h>
#include "iw_cxgb4.h"
diff --git a/drivers/infiniband/hw/efa/efa_verbs.c b/drivers/infiniband/hw/efa/efa_verbs.c
index 22d3e25c3b9d..19e3033d4ff7 100644
--- a/drivers/infiniband/hw/efa/efa_verbs.c
+++ b/drivers/infiniband/hw/efa/efa_verbs.c
@@ -9,9 +9,9 @@
#include <linux/log2.h>
#include <rdma/ib_addr.h>
-#include <rdma/ib_umem.h>
#include <rdma/ib_user_verbs.h>
#include <rdma/ib_verbs.h>
+#include <rdma/iter.h>
#include <rdma/uverbs_ioctl.h>
#define UVERBS_MODULE_NAME efa_ib
#include <rdma/uverbs_named_ioctl.h>
diff --git a/drivers/infiniband/hw/erdma/erdma_verbs.c b/drivers/infiniband/hw/erdma/erdma_verbs.c
index 109a3f3de911..058edc42de58 100644
--- a/drivers/infiniband/hw/erdma/erdma_verbs.c
+++ b/drivers/infiniband/hw/erdma/erdma_verbs.c
@@ -12,7 +12,7 @@
#include <linux/vmalloc.h>
#include <net/addrconf.h>
#include <rdma/erdma-abi.h>
-#include <rdma/ib_umem.h>
+#include <rdma/iter.h>
#include <rdma/uverbs_ioctl.h>
#include "erdma.h"
diff --git a/drivers/infiniband/hw/hns/hns_roce_alloc.c b/drivers/infiniband/hw/hns/hns_roce_alloc.c
index 6ee911f6885b..c21004814c3c 100644
--- a/drivers/infiniband/hw/hns/hns_roce_alloc.c
+++ b/drivers/infiniband/hw/hns/hns_roce_alloc.c
@@ -32,7 +32,7 @@
*/
#include <linux/vmalloc.h>
-#include <rdma/ib_umem.h>
+#include <rdma/iter.h>
#include "hns_roce_device.h"
void hns_roce_buf_free(struct hns_roce_dev *hr_dev, struct hns_roce_buf *buf)
diff --git a/drivers/infiniband/hw/ionic/ionic_ibdev.h b/drivers/infiniband/hw/ionic/ionic_ibdev.h
index 82fda1e3cdb6..63828240d659 100644
--- a/drivers/infiniband/hw/ionic/ionic_ibdev.h
+++ b/drivers/infiniband/hw/ionic/ionic_ibdev.h
@@ -4,9 +4,9 @@
#ifndef _IONIC_IBDEV_H_
#define _IONIC_IBDEV_H_
-#include <rdma/ib_umem.h>
#include <rdma/ib_verbs.h>
#include <rdma/ib_pack.h>
+#include <rdma/iter.h>
#include <rdma/uverbs_ioctl.h>
#include <rdma/ionic-abi.h>
diff --git a/drivers/infiniband/hw/irdma/main.h b/drivers/infiniband/hw/irdma/main.h
index d320d1a228b3..3d49bd57bae7 100644
--- a/drivers/infiniband/hw/irdma/main.h
+++ b/drivers/infiniband/hw/irdma/main.h
@@ -37,8 +37,8 @@
#include <rdma/rdma_cm.h>
#include <rdma/iw_cm.h>
#include <rdma/ib_user_verbs.h>
-#include <rdma/ib_umem.h>
#include <rdma/ib_cache.h>
+#include <rdma/iter.h>
#include <rdma/uverbs_ioctl.h>
#include "osdep.h"
#include "defs.h"
diff --git a/drivers/infiniband/hw/mana/mana_ib.h b/drivers/infiniband/hw/mana/mana_ib.h
index e447acfd2071..a7c8c0fd7019 100644
--- a/drivers/infiniband/hw/mana/mana_ib.h
+++ b/drivers/infiniband/hw/mana/mana_ib.h
@@ -8,7 +8,7 @@
#include <rdma/ib_verbs.h>
#include <rdma/ib_mad.h>
-#include <rdma/ib_umem.h>
+#include <rdma/iter.h>
#include <rdma/mana-abi.h>
#include <rdma/uverbs_ioctl.h>
#include <linux/dmapool.h>
diff --git a/drivers/infiniband/hw/mlx4/mr.c b/drivers/infiniband/hw/mlx4/mr.c
index 94464f1694d9..9b647a300eb9 100644
--- a/drivers/infiniband/hw/mlx4/mr.c
+++ b/drivers/infiniband/hw/mlx4/mr.c
@@ -33,6 +33,7 @@
#include <linux/slab.h>
#include <rdma/ib_user_verbs.h>
+#include <rdma/iter.h>
#include "mlx4_ib.h"
diff --git a/drivers/infiniband/hw/mlx5/mem.c b/drivers/infiniband/hw/mlx5/mem.c
index af321f6ef7f5..75d5b5672b5c 100644
--- a/drivers/infiniband/hw/mlx5/mem.c
+++ b/drivers/infiniband/hw/mlx5/mem.c
@@ -31,6 +31,7 @@
*/
#include <rdma/ib_umem_odp.h>
+#include <rdma/iter.h>
#include "mlx5_ib.h"
/*
diff --git a/drivers/infiniband/hw/mlx5/umr.c b/drivers/infiniband/hw/mlx5/umr.c
index 4e562e0dd9e1..29488fba21a0 100644
--- a/drivers/infiniband/hw/mlx5/umr.c
+++ b/drivers/infiniband/hw/mlx5/umr.c
@@ -2,6 +2,7 @@
/* Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES. */
#include <rdma/ib_umem_odp.h>
+#include <rdma/iter.h>
#include "mlx5_ib.h"
#include "umr.h"
#include "wr.h"
diff --git a/drivers/infiniband/hw/mthca/mthca_provider.c b/drivers/infiniband/hw/mthca/mthca_provider.c
index dd572d76866c..aa5ca5c4ff77 100644
--- a/drivers/infiniband/hw/mthca/mthca_provider.c
+++ b/drivers/infiniband/hw/mthca/mthca_provider.c
@@ -35,8 +35,8 @@
*/
#include <rdma/ib_smi.h>
-#include <rdma/ib_umem.h>
#include <rdma/ib_user_verbs.h>
+#include <rdma/iter.h>
#include <rdma/uverbs_ioctl.h>
#include <linux/sched.h>
diff --git a/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c b/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c
index 46d911fd38de..bf9211d8d130 100644
--- a/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c
+++ b/drivers/infiniband/hw/ocrdma/ocrdma_verbs.c
@@ -45,9 +45,9 @@
#include <rdma/ib_verbs.h>
#include <rdma/ib_user_verbs.h>
#include <rdma/iw_cm.h>
-#include <rdma/ib_umem.h>
#include <rdma/ib_addr.h>
#include <rdma/ib_cache.h>
+#include <rdma/iter.h>
#include <rdma/uverbs_ioctl.h>
#include "ocrdma.h"
diff --git a/drivers/infiniband/hw/qedr/verbs.c b/drivers/infiniband/hw/qedr/verbs.c
index ab9bf0922979..cb06c5d894b8 100644
--- a/drivers/infiniband/hw/qedr/verbs.c
+++ b/drivers/infiniband/hw/qedr/verbs.c
@@ -39,9 +39,9 @@
#include <rdma/ib_verbs.h>
#include <rdma/ib_user_verbs.h>
#include <rdma/iw_cm.h>
-#include <rdma/ib_umem.h>
#include <rdma/ib_addr.h>
#include <rdma/ib_cache.h>
+#include <rdma/iter.h>
#include <rdma/uverbs_ioctl.h>
#include <linux/qed/common_hsi.h>
diff --git a/drivers/infiniband/hw/vmw_pvrdma/pvrdma.h b/drivers/infiniband/hw/vmw_pvrdma/pvrdma.h
index 763ddc6f25d1..23e547d4b3a7 100644
--- a/drivers/infiniband/hw/vmw_pvrdma/pvrdma.h
+++ b/drivers/infiniband/hw/vmw_pvrdma/pvrdma.h
@@ -53,8 +53,8 @@
#include <linux/pci.h>
#include <linux/semaphore.h>
#include <linux/workqueue.h>
-#include <rdma/ib_umem.h>
#include <rdma/ib_verbs.h>
+#include <rdma/iter.h>
#include <rdma/vmw_pvrdma-abi.h>
#include "pvrdma_ring.h"
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index 0a8e092c0ea8..ce47688dd003 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -76,36 +76,6 @@ static inline size_t ib_umem_num_pages(struct ib_umem *umem)
return ib_umem_num_dma_blocks(umem, PAGE_SIZE);
}
-static inline void __rdma_umem_block_iter_start(struct ib_block_iter *biter,
- struct ib_umem *umem,
- unsigned long pgsz)
-{
- __rdma_block_iter_start(biter, umem->sgt_append.sgt.sgl,
- umem->sgt_append.sgt.nents, pgsz);
- biter->__sg_advance = ib_umem_offset(umem) & ~(pgsz - 1);
- biter->__sg_numblocks = ib_umem_num_dma_blocks(umem, pgsz);
-}
-
-static inline bool __rdma_umem_block_iter_next(struct ib_block_iter *biter)
-{
- return __rdma_block_iter_next(biter) && biter->__sg_numblocks--;
-}
-
-/**
- * rdma_umem_for_each_dma_block - iterate over contiguous DMA blocks of the umem
- * @umem: umem to iterate over
- * @pgsz: Page size to split the list into
- *
- * pgsz must be <= PAGE_SIZE or computed by ib_umem_find_best_pgsz(). The
- * returned DMA blocks will be aligned to pgsz and span the range:
- * ALIGN_DOWN(umem->address, pgsz) to ALIGN(umem->address + umem->length, pgsz)
- *
- * Performs exactly ib_umem_num_dma_blocks() iterations.
- */
-#define rdma_umem_for_each_dma_block(umem, biter, pgsz) \
- for (__rdma_umem_block_iter_start(biter, umem, pgsz); \
- __rdma_umem_block_iter_next(biter);)
-
#ifdef CONFIG_INFINIBAND_USER_MEM
struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr,
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 8bd020da7745..e1ec5a6c74e6 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2950,22 +2950,6 @@ struct ib_client {
u8 no_kverbs_req:1;
};
-/*
- * IB block DMA iterator
- *
- * Iterates the DMA-mapped SGL in contiguous memory blocks aligned
- * to a HW supported page size.
- */
-struct ib_block_iter {
- /* internal states */
- struct scatterlist *__sg; /* sg holding the current aligned block */
- dma_addr_t __dma_addr; /* unaligned DMA address of this block */
- size_t __sg_numblocks; /* ib_umem_num_dma_blocks() */
- unsigned int __sg_nents; /* number of SG entries */
- unsigned int __sg_advance; /* number of bytes to advance in sg in next step */
- unsigned int __pg_bit; /* alignment of current block */
-};
-
struct ib_device *_ib_alloc_device(size_t size, struct net *net);
#define ib_alloc_device(drv_struct, member) \
container_of(_ib_alloc_device(sizeof(struct drv_struct) + \
@@ -2994,38 +2978,6 @@ void ib_unregister_device_queued(struct ib_device *ib_dev);
int ib_register_client (struct ib_client *client);
void ib_unregister_client(struct ib_client *client);
-void __rdma_block_iter_start(struct ib_block_iter *biter,
- struct scatterlist *sglist,
- unsigned int nents,
- unsigned long pgsz);
-bool __rdma_block_iter_next(struct ib_block_iter *biter);
-
-/**
- * rdma_block_iter_dma_address - get the aligned dma address of the current
- * block held by the block iterator.
- * @biter: block iterator holding the memory block
- */
-static inline dma_addr_t
-rdma_block_iter_dma_address(struct ib_block_iter *biter)
-{
- return biter->__dma_addr & ~(BIT_ULL(biter->__pg_bit) - 1);
-}
-
-/**
- * rdma_for_each_block - iterate over contiguous memory blocks of the sg list
- * @sglist: sglist to iterate over
- * @biter: block iterator holding the memory block
- * @nents: maximum number of sg entries to iterate over
- * @pgsz: best HW supported page size to use
- *
- * Callers may use rdma_block_iter_dma_address() to get each
- * blocks aligned DMA address.
- */
-#define rdma_for_each_block(sglist, biter, nents, pgsz) \
- for (__rdma_block_iter_start(biter, sglist, nents, \
- pgsz); \
- __rdma_block_iter_next(biter);)
-
/**
* ib_get_client_data - Get IB client context
* @device:Device to get context for
diff --git a/include/rdma/iter.h b/include/rdma/iter.h
new file mode 100644
index 000000000000..19d64ef04ba9
--- /dev/null
+++ b/include/rdma/iter.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/* Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. */
+
+#ifndef _RDMA_ITER_H_
+#define _RDMA_ITER_H_
+
+#include <linux/scatterlist.h>
+#include <rdma/ib_umem.h>
+
+/**
+ * IB block DMA iterator
+ *
+ * Iterates the DMA-mapped SGL in contiguous memory blocks aligned
+ * to a HW supported page size.
+ */
+struct ib_block_iter {
+ /* internal states */
+ struct scatterlist *__sg; /* sg holding the current aligned block */
+ dma_addr_t __dma_addr; /* unaligned DMA address of this block */
+ size_t __sg_numblocks; /* ib_umem_num_dma_blocks() */
+ unsigned int __sg_nents; /* number of SG entries */
+ unsigned int __sg_advance; /* number of bytes to advance in sg in next step */
+ unsigned int __pg_bit; /* alignment of current block */
+};
+
+void __rdma_block_iter_start(struct ib_block_iter *biter,
+ struct scatterlist *sglist,
+ unsigned int nents,
+ unsigned long pgsz);
+bool __rdma_block_iter_next(struct ib_block_iter *biter);
+
+/**
+ * rdma_block_iter_dma_address - get the aligned dma address of the current
+ * block held by the block iterator.
+ * @biter: block iterator holding the memory block
+ */
+static inline dma_addr_t
+rdma_block_iter_dma_address(struct ib_block_iter *biter)
+{
+ return biter->__dma_addr & ~(BIT_ULL(biter->__pg_bit) - 1);
+}
+
+/**
+ * rdma_for_each_block - iterate over contiguous memory blocks of the sg list
+ * @sglist: sglist to iterate over
+ * @biter: block iterator holding the memory block
+ * @nents: maximum number of sg entries to iterate over
+ * @pgsz: best HW supported page size to use
+ *
+ * Callers may use rdma_block_iter_dma_address() to get each
+ * blocks aligned DMA address.
+ */
+#define rdma_for_each_block(sglist, biter, nents, pgsz) \
+ for (__rdma_block_iter_start(biter, sglist, nents, \
+ pgsz); \
+ __rdma_block_iter_next(biter);)
+
+static inline void __rdma_umem_block_iter_start(struct ib_block_iter *biter,
+ struct ib_umem *umem,
+ unsigned long pgsz)
+{
+ __rdma_block_iter_start(biter, umem->sgt_append.sgt.sgl,
+ umem->sgt_append.sgt.nents, pgsz);
+ biter->__sg_advance = ib_umem_offset(umem) & ~(pgsz - 1);
+ biter->__sg_numblocks = ib_umem_num_dma_blocks(umem, pgsz);
+}
+
+static inline bool __rdma_umem_block_iter_next(struct ib_block_iter *biter)
+{
+ return __rdma_block_iter_next(biter) && biter->__sg_numblocks--;
+}
+
+/**
+ * rdma_umem_for_each_dma_block - iterate over contiguous DMA blocks of the umem
+ * @umem: umem to iterate over
+ * @pgsz: Page size to split the list into
+ *
+ * pgsz must be <= PAGE_SIZE or computed by ib_umem_find_best_pgsz(). The
+ * returned DMA blocks will be aligned to pgsz and span the range:
+ * ALIGN_DOWN(umem->address, pgsz) to ALIGN(umem->address + umem->length, pgsz)
+ *
+ * Performs exactly ib_umem_num_dma_blocks() iterations.
+ */
+#define rdma_umem_for_each_dma_block(umem, biter, pgsz) \
+ for (__rdma_umem_block_iter_start(biter, umem, pgsz); \
+ __rdma_umem_block_iter_next(biter);)
+
+#endif /* _RDMA_ITER_H_ */
--
2.52.0
^ permalink raw reply related
* [PATCH rdma-next 00/50] RDMA: Ensure CQ UMEMs are managed by ib_core
From: Leon Romanovsky @ 2026-02-13 10:57 UTC (permalink / raw)
To: Jason Gunthorpe, Leon Romanovsky, Selvin Xavier, Kalesh AP,
Potnuri Bharat Teja, Michael Margolin, Gal Pressman,
Yossi Leybovich, Cheng Xu, Kai Shen, Chengchang Tang,
Junxian Huang, Abhijit Gangurde, Allen Hubbe, Krzysztof Czurylo,
Tatyana Nikolova, Long Li, Konstantin Taranov, Yishai Hadas,
Michal Kalderon, Bryan Tan, Vishnu Dasa,
Broadcom internal kernel review list, Christian Benvenuti,
Nelson Escobar, Dennis Dalessandro, Bernard Metzler, Zhu Yanjun
Cc: linux-kernel, linux-rdma, linux-hyperv
Unify CQ UMEM creation, resize and release in ib_core to avoid the need
for complex driver-side handling. This lets us rely on the internal
reference counters of the relevant ib_XXX objects to manage UMEM
lifetime safely and consistently.
The resize cleanup made it clear that most drivers never handled this
path correctly, and there's a good chance the functionality was never
actually used. The most common issue was relying on the cq->resize_umem
pointer to detect races with other CQ commands, without clearing it on
errors and while ignoring proper locking for other CQ operations.
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
Leon Romanovsky (50):
RDMA: Move DMA block iterator logic into dedicated files
RDMA/umem: Allow including ib_umem header from any location
RDMA/umem: Remove unnecessary includes and defines from ib_umem header
RDMA/core: Promote UMEM to a core component
RDMA/core: Manage CQ umem in core code
RDMA/efa: Rely on CPU address in create‑QP
RDMA/core: Prepare create CQ path for API unification
RDMA/core: Reject zero CQE count
RDMA/efa: Remove check for zero CQE count
RDMA/mlx5: Save 4 bytes in CQ structure
RDMA/mlx5: Provide a modern CQ creation interface
RDMA/mlx4: Inline mlx4_ib_get_cq_umem into callers
RDMA/mlx4: Introduce a modern CQ creation interface
RDMA/mlx4: Remove unused create_flags field from CQ structure
RDMA/bnxt_re: Convert to modern CQ interface
RDMA/cxgb4: Separate kernel and user CQ creation paths
RDMA/mthca: Split user and kernel CQ creation paths
RDMA/erdma: Separate user and kernel CQ creation paths
RDMA/ionic: Split user and kernel CQ creation paths
RDMA/qedr: Convert to modern CQ interface
RDMA/vmw_pvrdma: Provide a modern CQ creation interface
RDMA/ocrdma: Split user and kernel CQ creation paths
RDMA/irdma: Split user and kernel CQ creation paths
RDMA/usnic: Provide a modern CQ creation interface
RDMA/mana: Provide a modern CQ creation interface
RDMA/erdma: Separate user and kernel CQ creation paths
RDMA/rdmavt: Split user and kernel CQ creation paths
RDMA/siw: Split user and kernel CQ creation paths
RDMA/rxe: Split user and kernel CQ creation paths
RDMA/core: Remove legacy CQ creation fallback path
RDMA/core: Remove unused ib_resize_cq() implementation
RDMA: Clarify that CQ resize is a user‑space verb
RDMA/bnxt_re: Drop support for resizing kernel CQs
RDMA/irdma: Remove resize support for kernel CQs
RDMA/mlx4: Remove support for kernel CQ resize
RDMA/mlx5: Remove support for resizing kernel CQs
RDMA/mthca: Remove resize support for kernel CQs
RDMA/rdmavt: Remove resize support for kernel CQs
RDMA/rxe: Remove unused kernel‑side CQ resize support
RDMA: Properly propagate the number of CQEs as unsigned int
RDMA/core: Generalize CQ resize locking
RDMA/bnxt_re: Complete CQ resize in a single step
RDMA/bnxt_re: Rely on common resize‑CQ locking
RDMA/bnxt_re: Reduce CQ memory footprint
RDMA/mlx4: Use generic resize-CQ lock
RDMA/mlx4: Use on‑stack variables instead of storing them in the CQ object
RDMA/mlx5: Use generic resize-CQ lock
RDMA/mlx5: Select resize‑CQ callback based on device capabilities
RDMA/mlx5: Reduce CQ memory footprint
RDMA/mthca: Use generic resize-CQ lock
drivers/infiniband/core/Makefile | 6 +-
drivers/infiniband/core/cq.c | 3 +
drivers/infiniband/core/device.c | 4 +-
drivers/infiniband/core/iter.c | 43 +++
drivers/infiniband/core/umem.c | 2 +-
drivers/infiniband/core/uverbs_cmd.c | 18 +-
drivers/infiniband/core/uverbs_std_types_cq.c | 35 ++-
drivers/infiniband/core/verbs.c | 61 +---
drivers/infiniband/hw/bnxt_re/ib_verbs.c | 246 ++++++++-------
drivers/infiniband/hw/bnxt_re/ib_verbs.h | 9 +-
drivers/infiniband/hw/bnxt_re/main.c | 3 +-
drivers/infiniband/hw/bnxt_re/qplib_res.c | 2 +-
drivers/infiniband/hw/cxgb4/cq.c | 218 +++++++++----
drivers/infiniband/hw/cxgb4/iw_cxgb4.h | 2 +
drivers/infiniband/hw/cxgb4/mem.c | 2 +-
drivers/infiniband/hw/cxgb4/provider.c | 1 +
drivers/infiniband/hw/efa/efa.h | 6 +-
drivers/infiniband/hw/efa/efa_main.c | 3 +-
drivers/infiniband/hw/efa/efa_verbs.c | 44 ++-
drivers/infiniband/hw/erdma/erdma_main.c | 1 +
drivers/infiniband/hw/erdma/erdma_verbs.c | 99 ++++--
drivers/infiniband/hw/erdma/erdma_verbs.h | 2 +
drivers/infiniband/hw/hns/hns_roce_alloc.c | 2 +-
drivers/infiniband/hw/hns/hns_roce_cq.c | 103 ++++--
drivers/infiniband/hw/hns/hns_roce_debugfs.c | 1 -
drivers/infiniband/hw/hns/hns_roce_device.h | 3 +-
drivers/infiniband/hw/hns/hns_roce_main.c | 1 +
drivers/infiniband/hw/ionic/ionic_controlpath.c | 88 ++++--
drivers/infiniband/hw/ionic/ionic_ibdev.c | 1 +
drivers/infiniband/hw/ionic/ionic_ibdev.h | 4 +-
drivers/infiniband/hw/irdma/main.h | 2 +-
drivers/infiniband/hw/irdma/verbs.c | 402 +++++++++++++-----------
drivers/infiniband/hw/mana/cq.c | 128 +++++---
drivers/infiniband/hw/mana/device.c | 1 +
drivers/infiniband/hw/mana/main.c | 25 +-
drivers/infiniband/hw/mana/mana_ib.h | 6 +-
drivers/infiniband/hw/mana/qp.c | 42 ++-
drivers/infiniband/hw/mana/wq.c | 14 +-
drivers/infiniband/hw/mlx4/cq.c | 401 ++++++++---------------
drivers/infiniband/hw/mlx4/main.c | 3 +-
drivers/infiniband/hw/mlx4/mlx4_ib.h | 10 +-
drivers/infiniband/hw/mlx4/mr.c | 1 +
drivers/infiniband/hw/mlx5/cq.c | 383 ++++++++--------------
drivers/infiniband/hw/mlx5/main.c | 9 +-
drivers/infiniband/hw/mlx5/mem.c | 1 +
drivers/infiniband/hw/mlx5/mlx5_ib.h | 12 +-
drivers/infiniband/hw/mlx5/qp.c | 2 +-
drivers/infiniband/hw/mlx5/umr.c | 1 +
drivers/infiniband/hw/mthca/mthca_cq.c | 1 -
drivers/infiniband/hw/mthca/mthca_provider.c | 193 ++++--------
drivers/infiniband/hw/mthca/mthca_provider.h | 1 -
drivers/infiniband/hw/ocrdma/ocrdma_main.c | 3 +-
drivers/infiniband/hw/ocrdma/ocrdma_verbs.c | 70 +++--
drivers/infiniband/hw/ocrdma/ocrdma_verbs.h | 6 +-
drivers/infiniband/hw/qedr/main.c | 1 +
drivers/infiniband/hw/qedr/verbs.c | 325 +++++++++++--------
drivers/infiniband/hw/qedr/verbs.h | 2 +
drivers/infiniband/hw/usnic/usnic_ib_main.c | 2 +-
drivers/infiniband/hw/usnic/usnic_ib_verbs.c | 6 +-
drivers/infiniband/hw/usnic/usnic_ib_verbs.h | 4 +-
drivers/infiniband/hw/vmw_pvrdma/pvrdma.h | 2 +-
drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c | 171 ++++++----
drivers/infiniband/hw/vmw_pvrdma/pvrdma_main.c | 1 +
drivers/infiniband/hw/vmw_pvrdma/pvrdma_verbs.h | 3 +
drivers/infiniband/sw/rdmavt/cq.c | 224 +++++++------
drivers/infiniband/sw/rdmavt/cq.h | 4 +-
drivers/infiniband/sw/rdmavt/vt.c | 3 +-
drivers/infiniband/sw/rxe/rxe_cq.c | 31 --
drivers/infiniband/sw/rxe/rxe_loc.h | 3 -
drivers/infiniband/sw/rxe/rxe_verbs.c | 115 +++----
drivers/infiniband/sw/siw/siw_main.c | 1 +
drivers/infiniband/sw/siw/siw_verbs.c | 111 +++++--
drivers/infiniband/sw/siw/siw_verbs.h | 2 +
include/rdma/ib_umem.h | 36 +--
include/rdma/ib_verbs.h | 67 +---
include/rdma/iter.h | 88 ++++++
76 files changed, 2085 insertions(+), 1847 deletions(-)
---
base-commit: 42e3aac65c1c9eb36cdee0d8312a326196e0822f
change-id: 20260203-refactor-umem-e5b4277e41b4
Best regards,
--
Leon Romanovsky <leonro@nvidia.com>
^ permalink raw reply
* Re: [PATCH 3/3] x86/virt: rename x2apic_available to x2apic_without_ir_available
From: Shashank Balaji @ 2026-02-13 7:39 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
H. Peter Anvin, Suresh Siddha, K. Y. Srinivasan, Haiyang Zhang,
Wei Liu, Dexuan Cui, Long Li, Ajay Kaher, Alexey Makhalov,
Broadcom internal kernel review list, Jan Kiszka, Paolo Bonzini,
Vitaly Kuznetsov, Juergen Gross, Boris Ostrovsky
Cc: Ingo Molnar, linux-kernel, linux-hyperv, virtualization,
jailhouse-dev, kvm, xen-devel, Rahul Bukte, Daniel Palmer,
Tim Bird, Sohil Mehta
In-Reply-To: <20260202-x2apic-fix-v1-3-71c8f488a88b@sony.com>
Hi x86 and virt folks,
I'd like some feedback on this patch. I realise that just updating the
name to x2apic_without_ir_available() with no indication in the code
suggesting that the hypervisor implementations may not be answering the
question "is x2apic availalble without IR?" is bad.
I suppose the options are:
1. Check seven hypervisor's x2apic_available() implementation to see if
the "x2apic_without_ir_available" semantic matches, and then do the
renaming
Problem is, I don't know enough about the hypervisors to check
the implementations. Some help from the virt folks would be
great!
2. Add TODOs on the hypervisor implementations, hoping they'll be
audited in the future
There's a chance the TODOs will just sit there rotting. It's
ugly, even I don't like it
So how do we proceed?
On Mon, Feb 02, 2026 at 06:51:04PM +0900, Shashank Balaji wrote:
> No functional change.
>
> x86_init.hyper.x2apic_available is used only in try_to_enable_x2apic to check if
> x2apic needs to be disabled if interrupt remapping support isn't present. But
> the name x2apic_available doesn't reflect that usage.
>
> This is what x2apic_available is set to for various hypervisors:
>
> acrn boot_cpu_has(X86_FEATURE_X2APIC)
> mshyperv boot_cpu_has(X86_FEATURE_X2APIC)
> xen boot_cpu_has(X86_FEATURE_X2APIC) or false
> vmware vmware_legacy_x2apic_available
> kvm kvm_cpuid_base() != 0
> jailhouse x2apic_enabled()
> bhyve true
> default false
>
> Bare metal and vmware correctly check if x2apic is available without interrupt
> remapping. The rest of them check if x2apic is enabled/supported, and kvm just
> checks if the kernel is running on kvm. The other hypervisors may have to have
> their checks audited.
>
> Also fix the backwards pr_info message printed on disabling x2apic because of
> lack of irq remapping support.
>
> Compile tested with all the hypervisor guest support enabled.
>
> Co-developed-by: Rahul Bukte <rahul.bukte@sony.com>
> Signed-off-by: Rahul Bukte <rahul.bukte@sony.com>
> Signed-off-by: Shashank Balaji <shashank.mahadasyam@sony.com>
> ---
> arch/x86/include/asm/x86_init.h | 4 ++--
> arch/x86/kernel/apic/apic.c | 4 ++--
> arch/x86/kernel/cpu/acrn.c | 2 +-
> arch/x86/kernel/cpu/bhyve.c | 2 +-
> arch/x86/kernel/cpu/mshyperv.c | 2 +-
> arch/x86/kernel/cpu/vmware.c | 2 +-
> arch/x86/kernel/jailhouse.c | 2 +-
> arch/x86/kernel/kvm.c | 2 +-
> arch/x86/kernel/x86_init.c | 12 ++++++------
> arch/x86/xen/enlighten_hvm.c | 4 ++--
> 10 files changed, 18 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
> index 6c8a6ead84f6..b270d9eed755 100644
> --- a/arch/x86/include/asm/x86_init.h
> +++ b/arch/x86/include/asm/x86_init.h
> @@ -116,7 +116,7 @@ struct x86_init_pci {
> * struct x86_hyper_init - x86 hypervisor init functions
> * @init_platform: platform setup
> * @guest_late_init: guest late init
> - * @x2apic_available: X2APIC detection
> + * @x2apic_without_ir_available: is x2apic available without irq remap?
> * @msi_ext_dest_id: MSI supports 15-bit APIC IDs
> * @init_mem_mapping: setup early mappings during init_mem_mapping()
> * @init_after_bootmem: guest init after boot allocator is finished
> @@ -124,7 +124,7 @@ struct x86_init_pci {
> struct x86_hyper_init {
> void (*init_platform)(void);
> void (*guest_late_init)(void);
> - bool (*x2apic_available)(void);
> + bool (*x2apic_without_ir_available)(void);
> bool (*msi_ext_dest_id)(void);
> void (*init_mem_mapping)(void);
> void (*init_after_bootmem)(void);
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> index cc64d61f82cf..8820b631f8a2 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -1836,8 +1836,8 @@ static __init void try_to_enable_x2apic(int remap_mode)
> * Using X2APIC without IR is not architecturally supported
> * on bare metal but may be supported in guests.
> */
> - if (!x86_init.hyper.x2apic_available()) {
> - pr_info("x2apic: IRQ remapping doesn't support X2APIC mode\n");
> + if (!x86_init.hyper.x2apic_without_ir_available()) {
> + pr_info("x2apic: Not supported without IRQ remapping\n");
> x2apic_disable();
> return;
> }
> diff --git a/arch/x86/kernel/cpu/acrn.c b/arch/x86/kernel/cpu/acrn.c
> index 2c5b51aad91a..9204b98d4786 100644
> --- a/arch/x86/kernel/cpu/acrn.c
> +++ b/arch/x86/kernel/cpu/acrn.c
> @@ -77,5 +77,5 @@ const __initconst struct hypervisor_x86 x86_hyper_acrn = {
> .detect = acrn_detect,
> .type = X86_HYPER_ACRN,
> .init.init_platform = acrn_init_platform,
> - .init.x2apic_available = acrn_x2apic_available,
> + .init.x2apic_without_ir_available = acrn_x2apic_available,
> };
> diff --git a/arch/x86/kernel/cpu/bhyve.c b/arch/x86/kernel/cpu/bhyve.c
> index f1a8ca3dd1ed..91a90a7459ce 100644
> --- a/arch/x86/kernel/cpu/bhyve.c
> +++ b/arch/x86/kernel/cpu/bhyve.c
> @@ -61,6 +61,6 @@ const struct hypervisor_x86 x86_hyper_bhyve __refconst = {
> .name = "Bhyve",
> .detect = bhyve_detect,
> .init.init_platform = x86_init_noop,
> - .init.x2apic_available = bhyve_x2apic_available,
> + .init.x2apic_without_ir_available = bhyve_x2apic_available,
> .init.msi_ext_dest_id = bhyve_ext_dest_id,
> };
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index 579fb2c64cfd..61458855094a 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -760,7 +760,7 @@ const __initconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
> .name = "Microsoft Hyper-V",
> .detect = ms_hyperv_platform,
> .type = X86_HYPER_MS_HYPERV,
> - .init.x2apic_available = ms_hyperv_x2apic_available,
> + .init.x2apic_without_ir_available = ms_hyperv_x2apic_available,
> .init.msi_ext_dest_id = ms_hyperv_msi_ext_dest_id,
> .init.init_platform = ms_hyperv_init_platform,
> .init.guest_late_init = ms_hyperv_late_init,
> diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
> index cb3f900c46fc..46d325818797 100644
> --- a/arch/x86/kernel/cpu/vmware.c
> +++ b/arch/x86/kernel/cpu/vmware.c
> @@ -585,7 +585,7 @@ const __initconst struct hypervisor_x86 x86_hyper_vmware = {
> .detect = vmware_platform,
> .type = X86_HYPER_VMWARE,
> .init.init_platform = vmware_platform_setup,
> - .init.x2apic_available = vmware_legacy_x2apic_available,
> + .init.x2apic_without_ir_available = vmware_legacy_x2apic_available,
> #ifdef CONFIG_AMD_MEM_ENCRYPT
> .runtime.sev_es_hcall_prepare = vmware_sev_es_hcall_prepare,
> .runtime.sev_es_hcall_finish = vmware_sev_es_hcall_finish,
> diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c
> index 9e9a591a5fec..84a0bbe15989 100644
> --- a/arch/x86/kernel/jailhouse.c
> +++ b/arch/x86/kernel/jailhouse.c
> @@ -291,6 +291,6 @@ const struct hypervisor_x86 x86_hyper_jailhouse __refconst = {
> .name = "Jailhouse",
> .detect = jailhouse_detect,
> .init.init_platform = jailhouse_init_platform,
> - .init.x2apic_available = jailhouse_x2apic_available,
> + .init.x2apic_without_ir_available = jailhouse_x2apic_available,
> .ignore_nopv = true,
> };
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index 37dc8465e0f5..709eba87d58e 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -1042,7 +1042,7 @@ const __initconst struct hypervisor_x86 x86_hyper_kvm = {
> .detect = kvm_detect,
> .type = X86_HYPER_KVM,
> .init.guest_late_init = kvm_guest_init,
> - .init.x2apic_available = kvm_para_available,
> + .init.x2apic_without_ir_available = kvm_para_available,
> .init.msi_ext_dest_id = kvm_msi_ext_dest_id,
> .init.init_platform = kvm_init_platform,
> #if defined(CONFIG_AMD_MEM_ENCRYPT)
> diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
> index ebefb77c37bb..9ddf8c901ac6 100644
> --- a/arch/x86/kernel/x86_init.c
> +++ b/arch/x86/kernel/x86_init.c
> @@ -112,12 +112,12 @@ struct x86_init_ops x86_init __initdata = {
> },
>
> .hyper = {
> - .init_platform = x86_init_noop,
> - .guest_late_init = x86_init_noop,
> - .x2apic_available = bool_x86_init_noop,
> - .msi_ext_dest_id = bool_x86_init_noop,
> - .init_mem_mapping = x86_init_noop,
> - .init_after_bootmem = x86_init_noop,
> + .init_platform = x86_init_noop,
> + .guest_late_init = x86_init_noop,
> + .x2apic_without_ir_available = bool_x86_init_noop,
> + .msi_ext_dest_id = bool_x86_init_noop,
> + .init_mem_mapping = x86_init_noop,
> + .init_after_bootmem = x86_init_noop,
> },
>
> .acpi = {
> diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
> index fe57ff85d004..42f3d21f313d 100644
> --- a/arch/x86/xen/enlighten_hvm.c
> +++ b/arch/x86/xen/enlighten_hvm.c
> @@ -311,7 +311,7 @@ static uint32_t __init xen_platform_hvm(void)
> * detect PVH and panic there.
> */
> h->init_platform = x86_init_noop;
> - h->x2apic_available = bool_x86_init_noop;
> + h->x2apic_without_ir_available = bool_x86_init_noop;
> h->init_mem_mapping = x86_init_noop;
> h->init_after_bootmem = x86_init_noop;
> h->guest_late_init = xen_hvm_guest_late_init;
> @@ -325,7 +325,7 @@ struct hypervisor_x86 x86_hyper_xen_hvm __initdata = {
> .detect = xen_platform_hvm,
> .type = X86_HYPER_XEN_HVM,
> .init.init_platform = xen_hvm_guest_init,
> - .init.x2apic_available = xen_x2apic_available,
> + .init.x2apic_without_ir_available = xen_x2apic_available,
> .init.init_mem_mapping = xen_hvm_init_mem_mapping,
> .init.guest_late_init = xen_hvm_guest_late_init,
> .init.msi_ext_dest_id = msi_ext_dest_id,
>
> --
> 2.43.0
>
^ permalink raw reply
* Re: [PATCH 1/2] kexec: Add permission notifier chain for kexec operations
From: Mukesh R @ 2026-02-12 22:12 UTC (permalink / raw)
To: Stanislav Kinsburskii, rppt, akpm, bhe, kys, haiyangz, wei.liu,
decui, longli
Cc: kexec, linux-hyperv, linux-kernel
In-Reply-To: <176962212169.85424.4683391728440118017.stgit@skinsburskii-cloud-desktop.internal.cloudapp.net>
On 1/28/26 09:42, Stanislav Kinsburskii wrote:
> Add a blocking notifier chain to allow subsystems to be notified
> before kexec execution. This enables modules to perform necessary
> cleanup or validation before the system transitions to a new kernel or
> block kexec if not possible under current conditions.
>
> Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
> ---
> include/linux/kexec.h | 6 ++++++
> kernel/kexec_core.c | 24 ++++++++++++++++++++++++
> 2 files changed, 30 insertions(+)
>
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index ff7e231b0485..311037d30f9e 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -35,6 +35,7 @@ extern note_buf_t __percpu *crash_notes;
> #include <linux/ioport.h>
> #include <linux/module.h>
> #include <linux/highmem.h>
> +#include <linux/notifier.h>
> #include <asm/kexec.h>
> #include <linux/crash_core.h>
>
> @@ -532,10 +533,13 @@ extern bool kexec_file_dbg_print;
>
> extern void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size);
> extern void kimage_unmap_segment(void *buffer);
> +extern int kexec_block_notifier_register(struct notifier_block *nb);
> +extern int kexec_block_notifier_unregister(struct notifier_block *nb);
> #else /* !CONFIG_KEXEC_CORE */
> struct pt_regs;
> struct task_struct;
> struct kimage;
> +struct notifier_block;
> static inline void __crash_kexec(struct pt_regs *regs) { }
> static inline void crash_kexec(struct pt_regs *regs) { }
> static inline int kexec_should_crash(struct task_struct *p) { return 0; }
> @@ -543,6 +547,8 @@ static inline int kexec_crash_loaded(void) { return 0; }
> static inline void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size)
> { return NULL; }
> static inline void kimage_unmap_segment(void *buffer) { }
> +static inline int kexec_block_notifier_register(struct notifier_block *nb) { }
> +static inline int kexec_block_notifier_unregister(struct notifier_block *nb) { }
> #define kexec_in_progress false
> #endif /* CONFIG_KEXEC_CORE */
>
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 0f92acdd354d..1e86a6f175f0 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -57,6 +57,20 @@ bool kexec_in_progress = false;
>
> bool kexec_file_dbg_print;
>
> +static BLOCKING_NOTIFIER_HEAD(kexec_block_list);
> +
> +int kexec_block_notifier_register(struct notifier_block *nb)
> +{
> + return blocking_notifier_chain_register(&kexec_block_list, nb);
> +}
> +EXPORT_SYMBOL_GPL(kexec_block_notifier_register);
> +
> +int kexec_block_notifier_unregister(struct notifier_block *nb)
> +{
> + return blocking_notifier_chain_unregister(&kexec_block_list, nb);
> +}
> +EXPORT_SYMBOL_GPL(kexec_block_notifier_unregister);
> +
> /*
> * When kexec transitions to the new kernel there is a one-to-one
> * mapping between physical and virtual addresses. On processors
> @@ -1124,6 +1138,12 @@ bool kexec_load_permitted(int kexec_image_type)
> return true;
> }
>
> +static int kexec_check_blockers(void)
> +{
> + /* Notify subsystems of impending kexec */
> + return blocking_notifier_call_chain(&kexec_block_list, 0, NULL);
> +}
> +
> /*
> * Move into place and start executing a preloaded standalone
> * executable. If nothing was preloaded return an error.
> @@ -1139,6 +1159,10 @@ int kernel_kexec(void)
> goto Unlock;
> }
>
> + error = kexec_check_blockers();
This could take a long time, and I am not sure if it's a good idea
to stall kexec with such dependencies.
Thanks,
-Mukesh
> + if (error)
> + goto Unlock;
> +
> error = liveupdate_reboot();
> if (error)
> goto Unlock;
>
>
^ permalink raw reply
* Re: [PATCH 2/2] mshv: Add kexec blocking support
From: Mukesh R @ 2026-02-12 22:11 UTC (permalink / raw)
To: Stanislav Kinsburskii, rppt, akpm, bhe, kys, haiyangz, wei.liu,
decui, longli
Cc: kexec, linux-hyperv, linux-kernel
In-Reply-To: <176962212724.85424.5690118672585914211.stgit@skinsburskii-cloud-desktop.internal.cloudapp.net>
On 1/28/26 09:42, Stanislav Kinsburskii wrote:
> Add kexec notifier to prevent kexec when VMs are active or memory
> is deposited. The notifier blocks kexec operations if:
> - Active VMs exist in the partition table
> - Pages are still deposited to the hypervisor
>
> The kernel cannot access hypervisor deposited pages: any access
> triggers a GPF. Until the deposited page state can be handed over
> to the next kernel, kexec must be blocked if there is any shared
> state between kernel and hypervisor.
>
> For L1 host virtualization, attempt to withdraw all deposited memory before
> allowing kexec to proceed. If withdrawal fails or pages remain deposited
> block the kexec operation.
>
> Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
> ---
> drivers/hv/Makefile | 1 +
> drivers/hv/hv_proc.c | 4 ++
> drivers/hv/mshv_kexec.c | 66 ++++++++++++++++++++++++++++++++++++++++
> drivers/hv/mshv_root.h | 14 ++++++++
> drivers/hv/mshv_root_hv_call.c | 2 +
> drivers/hv/mshv_root_main.c | 7 ++++
> 6 files changed, 94 insertions(+)
> create mode 100644 drivers/hv/mshv_kexec.c
>
> diff --git a/drivers/hv/Makefile b/drivers/hv/Makefile
> index a49f93c2d245..bb72be5cc525 100644
> --- a/drivers/hv/Makefile
> +++ b/drivers/hv/Makefile
> @@ -15,6 +15,7 @@ hv_vmbus-$(CONFIG_HYPERV_TESTING) += hv_debugfs.o
> hv_utils-y := hv_util.o hv_kvp.o hv_snapshot.o hv_utils_transport.o
> mshv_root-y := mshv_root_main.o mshv_synic.o mshv_eventfd.o mshv_irq.o \
> mshv_root_hv_call.o mshv_portid_table.o mshv_regions.o
> +mshv_root-$(CONFIG_KEXEC) += mshv_kexec.o
> mshv_vtl-y := mshv_vtl_main.o
>
> # Code that must be built-in
> diff --git a/drivers/hv/hv_proc.c b/drivers/hv/hv_proc.c
> index 89870c1b0087..39bbbedb0340 100644
> --- a/drivers/hv/hv_proc.c
> +++ b/drivers/hv/hv_proc.c
> @@ -15,6 +15,8 @@
> */
> #define HV_DEPOSIT_MAX (HV_HYP_PAGE_SIZE / sizeof(u64) - 1)
>
> +atomic_t hv_pages_deposited;
> +
> /* Deposits exact number of pages. Must be called with interrupts enabled. */
> int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
> {
> @@ -93,6 +95,8 @@ int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
> goto err_free_allocations;
> }
>
> + atomic_add(page_count, &hv_pages_deposited);
> +
> ret = 0;
> goto free_buf;
>
> diff --git a/drivers/hv/mshv_kexec.c b/drivers/hv/mshv_kexec.c
> new file mode 100644
> index 000000000000..5222b2e4ff97
> --- /dev/null
> +++ b/drivers/hv/mshv_kexec.c
> @@ -0,0 +1,66 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2026, Microsoft Corporation.
> + *
> + * Live update orchestration management for mshv_root module.
> + *
> + * Author: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
> + */
> +
> +#include <linux/kexec.h>
> +#include <linux/notifier.h>
> +#include <asm/mshyperv.h>
> +#include "mshv_root.h"
> +
> +static BLOCKING_NOTIFIER_HEAD(overlay_notify_chain);
> +
> +static int mshv_block_kexec_notify(struct notifier_block *nb,
> + unsigned long action, void *arg)
> +{
> + if (!hash_empty(mshv_root.pt_htable)) {
> + pr_warn("mshv: Cannot perform kexec while VMs are active\n");
> + return -EBUSY;
> + }
> +
> + if (hv_l1vh_partition()) {
> + int err;
> +
> + /* Attempt to withdraw all the deposited pages */
> + err = hv_call_withdraw_memory(U64_MAX, NUMA_NO_NODE,
> + hv_current_partition_id);
> + if (err) {
> + pr_err("mshv: Failed to withdraw memory from L1 virtualization: %d\n",
> + err);
> + return err;
> + }
> + }
> +
> + if (atomic_read(&hv_pages_deposited)) {
> + pr_warn("mshv: Cannot perform kexec while pages are deposited\n");
> + return -EBUSY;
> + }
> + return 0;
> +}
> +
What guarantees another deposit won't happen after this. Are all cpus
"locked" in kexec path and not doing anything at this point?
Thanks,
-Mukesh
> +static struct notifier_block mshv_kexec_notifier = {
> + .notifier_call = mshv_block_kexec_notify,
> +};
> +
> +int __init mshv_kexec_init(void)
> +{
> + int err;
> +
> + err = kexec_block_notifier_register(&mshv_kexec_notifier);
> + if (err) {
> + pr_err("mshv: Could not register kexec notifier: %pe\n",
> + ERR_PTR(err));
> + return err;
> + }
> +
> + return 0;
> +}
> +
> +void __exit mshv_kexec_exit(void)
> +{
> + (void)kexec_block_notifier_unregister(&mshv_kexec_notifier);
> +}
> diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
> index 3c1d88b36741..311f76262d10 100644
> --- a/drivers/hv/mshv_root.h
> +++ b/drivers/hv/mshv_root.h
> @@ -17,6 +17,7 @@
> #include <linux/build_bug.h>
> #include <linux/mmu_notifier.h>
> #include <uapi/linux/mshv.h>
> +#include <hyperv/hvhdk.h>
>
> /*
> * Hypervisor must be between these version numbers (inclusive)
> @@ -319,6 +320,7 @@ int hv_call_get_partition_property_ex(u64 partition_id, u64 property_code, u64 a
> extern struct mshv_root mshv_root;
> extern enum hv_scheduler_type hv_scheduler_type;
> extern u8 * __percpu *hv_synic_eventring_tail;
> +extern atomic_t hv_pages_deposited;
>
> struct mshv_mem_region *mshv_region_create(u64 guest_pfn, u64 nr_pages,
> u64 uaddr, u32 flags);
> @@ -333,4 +335,16 @@ bool mshv_region_handle_gfn_fault(struct mshv_mem_region *region, u64 gfn);
> void mshv_region_movable_fini(struct mshv_mem_region *region);
> bool mshv_region_movable_init(struct mshv_mem_region *region);
>
> +#if IS_ENABLED(CONFIG_KEXEC)
> +int mshv_kexec_init(void);
> +void mshv_kexec_exit(void);
> +#else
> +static inline int mshv_kexec_init(void)
> +{
> + return 0;
> +}
> +
> +static inline void mshv_kexec_exit(void) { }
> +#endif
> +
> #endif /* _MSHV_ROOT_H_ */
> diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c
> index 06f2bac8039d..4203af5190ee 100644
> --- a/drivers/hv/mshv_root_hv_call.c
> +++ b/drivers/hv/mshv_root_hv_call.c
> @@ -73,6 +73,8 @@ int hv_call_withdraw_memory(u64 count, int node, u64 partition_id)
> for (i = 0; i < completed; i++)
> __free_page(pfn_to_page(output_page->gpa_page_list[i]));
>
> + atomic_sub(completed, &hv_pages_deposited);
> +
> if (!hv_result_success(status)) {
> if (hv_result(status) == HV_STATUS_NO_RESOURCES)
> status = HV_STATUS_SUCCESS;
> diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
> index 5fc572e31cd7..d55aa69d130c 100644
> --- a/drivers/hv/mshv_root_main.c
> +++ b/drivers/hv/mshv_root_main.c
> @@ -2330,6 +2330,10 @@ static int __init mshv_parent_partition_init(void)
> if (ret)
> goto deinit_root_scheduler;
>
> + ret = mshv_kexec_init();
> + if (ret)
> + goto deinit_irqfd_wq;
> +
> spin_lock_init(&mshv_root.pt_ht_lock);
> hash_init(mshv_root.pt_htable);
>
> @@ -2337,6 +2341,8 @@ static int __init mshv_parent_partition_init(void)
>
> return 0;
>
> +deinit_irqfd_wq:
> + mshv_irqfd_wq_cleanup();
> deinit_root_scheduler:
> root_scheduler_deinit();
> exit_partition:
> @@ -2356,6 +2362,7 @@ static void __exit mshv_parent_partition_exit(void)
> hv_setup_mshv_handler(NULL);
> mshv_port_table_fini();
> misc_deregister(&mshv_dev);
> + mshv_kexec_exit();
> mshv_irqfd_wq_cleanup();
> root_scheduler_deinit();
> if (hv_root_partition())
>
>
^ permalink raw reply
* RE: [PATCH 2/2] drm/hyperv: During panic do VMBus unload after frame buffer is flushed
From: Michael Kelley @ 2026-02-12 16:30 UTC (permalink / raw)
To: Jocelyn Falempe, drawat.floss@gmail.com,
maarten.lankhorst@linux.intel.com, mripard@kernel.org,
tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch,
kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
decui@microsoft.com, longli@microsoft.com, ryasuoka@redhat.com
Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
linux-hyperv@vger.kernel.org, stable@vger.kernel.org
In-Reply-To: <7c6933fc-663d-4bf6-8594-c14c4be83c98@redhat.com>
From: Jocelyn Falempe <jfalempe@redhat.com> Sent: Thursday, February 12, 2026 2:10 AM
>
> On 12/02/2026 10:49, Jocelyn Falempe wrote:
> > On 12/02/2026 00:01, mhklkml@zohomail.com wrote:
> >> From: Jocelyn Falempe <jfalempe@redhat.com> Sent: Wednesday, February
> >> 11, 2026 1:54 PM
> >>
> >> But for this patch, the issue is that drm_panic() never gets called if CONFIG_PRINTK
> >> isn't set. In that case, kmsg_dump_register() is a stub that returns an error. So
> >> drm_panic_register() never registers the callback to drm_panic(). And if
> >> drm_panic() isn't going to run, responsibility for doing the VMBus unload
> >> must remain with the VMBus code. It's hard to actually test this case because
> >> of depending on printk() for debugging output, so double-check my thinking.
> >
> > Ok you're right. I changed from
> > atomic_notifier_chain_register(&panic_notifier_list, ...) to
> > kmsg_dump_register() in the v10 of drm_panic.
> >
> > So I should either make DRM_PANIC depends on PRINTK, or call
> > atomic_notifier_chain_register() if PRINTK is not defined.
> >
> > As I think kernel without PRINTK are uncommon, I'll probably do the
> > first solution.
> >
>
> FYI, I just sent the corresponding change:
>
> https://patchwork.freedesktop.org/series/161544/
>
Works for me. That means I can drop the CONFIG_PRINTK condition
from my patch, which would be good. The current version is rather
strange in that regard. I'm pretty tied up the rest of this week,
so it may be next week before I resubmit my patches.
Michael
^ permalink raw reply
* RE: [PATCH] x86: mshyperv: Use kthread for vmbus interrupts on PREEMPT_RT
From: Michael Kelley @ 2026-02-12 16:22 UTC (permalink / raw)
To: Jan Kiszka, Michael Kelley, Florian Bezdeka, K. Y. Srinivasan,
Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Thomas Gleixner,
Ingo Molnar, Borislav Petkov, Dave Hansen, x86@kernel.org
Cc: linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, RT,
Mitchell Levy, skinsburskii@linux.microsoft.com,
mrathor@linux.microsoft.com, anirudh@anirudhrb.com,
schakrabarti@linux.microsoft.com, ssengar@linux.microsoft.com
In-Reply-To: <b084a7b6-c394-4337-82cd-8b9cb911d8d5@siemens.com>
From: Jan Kiszka <jan.kiszka@siemens.com> Sent: Thursday, February 12, 2026 8:06 AM
>
> On 09.02.26 19:25, Michael Kelley wrote:
> > From: Florian Bezdeka <florian.bezdeka@siemens.com> Sent: Monday, February 9, 2026 2:35 AM
> >>
> >> On Sat, 2026-02-07 at 01:30 +0000, Michael Kelley wrote:
> >>
> >> [snip]
> >>>
> >>> I've run your suggested experiment on an arm64 VM in the Azure cloud. My
> >>> kernel was linux-next 20260128. I set CONFIG_PREEMPT_RT=y and
> >>> CONFIG_PROVE_LOCKING=y, but did not add either of your two patches
> >>> (neither the storvsc driver patch nor the x86 VMBus interrupt handling patch).
> >>> The VM comes up and runs, but with this warning during boot:
> >>>
> >>> [ 3.075604] hv_utils: Registering HyperV Utility Driver
> >>> [ 3.075636] hv_vmbus: registering driver hv_utils
> >>> [ 3.085920] =============================
> >>> [ 3.088128] hv_vmbus: registering driver hv_netvsc
> >>> [ 3.091180] [ BUG: Invalid wait context ]
> >>> [ 3.093544] 6.19.0-rc7-next-20260128+ #3 Tainted: G E
> >>> [ 3.097582] -----------------------------
> >>> [ 3.099899] systemd-udevd/284 is trying to lock:
> >>> [ 3.102568] ffff000100e24490 (&channel->sched_lock){....}-{3:3}, at: vmbus_chan_sched+0x128/0x3b8 [hv_vmbus]
> >>> [ 3.108208] other info that might help us debug this:
> >>> [ 3.111454] context-{2:2}
> >>> [ 3.112987] 1 lock held by systemd-udevd/284:
> >>> [ 3.115626] #0: ffffd5cfc20bcc80 (rcu_read_lock){....}-{1:3}, at: vmbus_chan_sched+0xcc/0x3b8 [hv_vmbus]
> >>> [ 3.121224] stack backtrace:
> >>> [ 3.122897] CPU: 0 UID: 0 PID: 284 Comm: systemd-udevd Tainted: G E 6.19.0-rc7-next-20260128+ #3 PREEMPT_RT
> >>> [ 3.129631] Tainted: [E]=UNSIGNED_MODULE
> >>> [ 3.131946] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 06/10/2025
> >>> [ 3.138553] Call trace:
> >>> [ 3.140015] show_stack+0x20/0x38 (C)
> >>> [ 3.142137] dump_stack_lvl+0x9c/0x158
> >>> [ 3.144340] dump_stack+0x18/0x28
> >>> [ 3.146290] __lock_acquire+0x488/0x1e20
> >>> [ 3.148569] lock_acquire+0x11c/0x388
> >>> [ 3.150703] rt_spin_lock+0x54/0x230
> >>> [ 3.152785] vmbus_chan_sched+0x128/0x3b8 [hv_vmbus]
> >>> [ 3.155611] vmbus_isr+0x34/0x80 [hv_vmbus]
> >>> [ 3.158093] vmbus_percpu_isr+0x18/0x30 [hv_vmbus]
> >>> [ 3.160848] handle_percpu_devid_irq+0xdc/0x348
> >>> [ 3.163495] handle_irq_desc+0x48/0x68
> >>> [ 3.165851] generic_handle_domain_irq+0x20/0x38
> >>> [ 3.168664] gic_handle_irq+0x1dc/0x430
> >>> [ 3.170868] call_on_irq_stack+0x30/0x70
> >>> [ 3.173161] do_interrupt_handler+0x88/0xa0
> >>> [ 3.175724] el1_interrupt+0x4c/0xb0
> >>> [ 3.177855] el1h_64_irq_handler+0x18/0x28
> >>> [ 3.180332] el1h_64_irq+0x84/0x88
> >>> [ 3.182378] _raw_spin_unlock_irqrestore+0x4c/0xb0 (P)
> >>> [ 3.185493] rt_mutex_slowunlock+0x404/0x440
> >>> [ 3.187951] rt_spin_unlock+0xb8/0x178
> >>> [ 3.190394] kmem_cache_alloc_noprof+0xf0/0x4f8
> >>> [ 3.193100] alloc_empty_file+0x64/0x148
> >>> [ 3.195461] path_openat+0x58/0xaa0
> >>> [ 3.197658] do_file_open+0xa0/0x140
> >>> [ 3.199752] do_sys_openat2+0x190/0x278
> >>> [ 3.202124] do_sys_open+0x60/0xb8
> >>> [ 3.204047] __arm64_sys_openat+0x2c/0x48
> >>> [ 3.206433] invoke_syscall+0x6c/0xf8
> >>> [ 3.208519] el0_svc_common.constprop.0+0x48/0xf0
> >>> [ 3.211050] do_el0_svc+0x24/0x38
> >>> [ 3.212990] el0_svc+0x164/0x3c8
> >>> [ 3.214842] el0t_64_sync_handler+0xd0/0xe8
> >>> [ 3.217251] el0t_64_sync+0x1b0/0x1b8
> >>> [ 3.219450] hv_utils: Heartbeat IC version 3.0
> >>> [ 3.219471] hv_utils: Shutdown IC version 3.2
> >>> [ 3.219844] hv_utils: TimeSync IC version 4.0
> >>
> >> That matches with my expectation that the same problem exists on arm64.
> >> The patch from Jan addresses that issue for x86 (only, so far) as we do
> >> not have a working test environment for arm64 yet.
> >
> > OK. I had understood Jan's earlier comments to mean that the VMBus
> > interrupt problem was implicitly solved on arm64 because of VMBus using
> > a standard Linux IRQ on arm64. But evidently that's not the case. So my
> > earlier comment stands: The code changes should go into the architecture
> > independent portion of the VMBus driver, and not under arch/x86. I
> > can probably work with you to test on arm64 if need be.
> >
>
> I can move the code, sure, but I still haven't understood what
> invalidates my assumptions (beside what you observed). vmbus_drv calls
> request_percpu_irq, and that is - as far as I can see - not injecting
> IRQF_NO_THREAD. Any explanations welcome.
>
> Reproduction is still not possible for me. I was playing a bit with qemu
> in the hope to make it provide its minimal vmbus support (for
> ballooning), but that was not yet successful on arm64.
>
Let me try to debug my experiment on arm64 and see why it isn't
handing off the VMBus interrupt to a thread. Maybe there's something
missing in my .config. But it will be sometime next week before
I can do it.
Michael
^ permalink raw reply
* Re: [PATCH] x86: mshyperv: Use kthread for vmbus interrupts on PREEMPT_RT
From: Jan Kiszka @ 2026-02-12 16:06 UTC (permalink / raw)
To: Michael Kelley, Florian Bezdeka, K. Y. Srinivasan, Haiyang Zhang,
Wei Liu, Dexuan Cui, Long Li, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, Dave Hansen, x86@kernel.org
Cc: linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, RT,
Mitchell Levy, skinsburskii@linux.microsoft.com,
mrathor@linux.microsoft.com, anirudh@anirudhrb.com,
schakrabarti@linux.microsoft.com, ssengar@linux.microsoft.com
In-Reply-To: <SN6PR02MB4157DB59F0F7BFBF56612651D465A@SN6PR02MB4157.namprd02.prod.outlook.com>
On 09.02.26 19:25, Michael Kelley wrote:
> From: Florian Bezdeka <florian.bezdeka@siemens.com> Sent: Monday, February 9, 2026 2:35 AM
>>
>> On Sat, 2026-02-07 at 01:30 +0000, Michael Kelley wrote:
>>
>> [snip]
>>>
>>> I've run your suggested experiment on an arm64 VM in the Azure cloud. My
>>> kernel was linux-next 20260128. I set CONFIG_PREEMPT_RT=y and
>>> CONFIG_PROVE_LOCKING=y, but did not add either of your two patches
>>> (neither the storvsc driver patch nor the x86 VMBus interrupt handling patch).
>>> The VM comes up and runs, but with this warning during boot:
>>>
>>> [ 3.075604] hv_utils: Registering HyperV Utility Driver
>>> [ 3.075636] hv_vmbus: registering driver hv_utils
>>> [ 3.085920] =============================
>>> [ 3.088128] hv_vmbus: registering driver hv_netvsc
>>> [ 3.091180] [ BUG: Invalid wait context ]
>>> [ 3.093544] 6.19.0-rc7-next-20260128+ #3 Tainted: G E
>>> [ 3.097582] -----------------------------
>>> [ 3.099899] systemd-udevd/284 is trying to lock:
>>> [ 3.102568] ffff000100e24490 (&channel->sched_lock){....}-{3:3}, at: vmbus_chan_sched+0x128/0x3b8 [hv_vmbus]
>>> [ 3.108208] other info that might help us debug this:
>>> [ 3.111454] context-{2:2}
>>> [ 3.112987] 1 lock held by systemd-udevd/284:
>>> [ 3.115626] #0: ffffd5cfc20bcc80 (rcu_read_lock){....}-{1:3}, at: vmbus_chan_sched+0xcc/0x3b8 [hv_vmbus]
>>> [ 3.121224] stack backtrace:
>>> [ 3.122897] CPU: 0 UID: 0 PID: 284 Comm: systemd-udevd Tainted: G E 6.19.0-rc7-next-20260128+ #3 PREEMPT_RT
>>> [ 3.129631] Tainted: [E]=UNSIGNED_MODULE
>>> [ 3.131946] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.1 06/10/2025
>>> [ 3.138553] Call trace:
>>> [ 3.140015] show_stack+0x20/0x38 (C)
>>> [ 3.142137] dump_stack_lvl+0x9c/0x158
>>> [ 3.144340] dump_stack+0x18/0x28
>>> [ 3.146290] __lock_acquire+0x488/0x1e20
>>> [ 3.148569] lock_acquire+0x11c/0x388
>>> [ 3.150703] rt_spin_lock+0x54/0x230
>>> [ 3.152785] vmbus_chan_sched+0x128/0x3b8 [hv_vmbus]
>>> [ 3.155611] vmbus_isr+0x34/0x80 [hv_vmbus]
>>> [ 3.158093] vmbus_percpu_isr+0x18/0x30 [hv_vmbus]
>>> [ 3.160848] handle_percpu_devid_irq+0xdc/0x348
>>> [ 3.163495] handle_irq_desc+0x48/0x68
>>> [ 3.165851] generic_handle_domain_irq+0x20/0x38
>>> [ 3.168664] gic_handle_irq+0x1dc/0x430
>>> [ 3.170868] call_on_irq_stack+0x30/0x70
>>> [ 3.173161] do_interrupt_handler+0x88/0xa0
>>> [ 3.175724] el1_interrupt+0x4c/0xb0
>>> [ 3.177855] el1h_64_irq_handler+0x18/0x28
>>> [ 3.180332] el1h_64_irq+0x84/0x88
>>> [ 3.182378] _raw_spin_unlock_irqrestore+0x4c/0xb0 (P)
>>> [ 3.185493] rt_mutex_slowunlock+0x404/0x440
>>> [ 3.187951] rt_spin_unlock+0xb8/0x178
>>> [ 3.190394] kmem_cache_alloc_noprof+0xf0/0x4f8
>>> [ 3.193100] alloc_empty_file+0x64/0x148
>>> [ 3.195461] path_openat+0x58/0xaa0
>>> [ 3.197658] do_file_open+0xa0/0x140
>>> [ 3.199752] do_sys_openat2+0x190/0x278
>>> [ 3.202124] do_sys_open+0x60/0xb8
>>> [ 3.204047] __arm64_sys_openat+0x2c/0x48
>>> [ 3.206433] invoke_syscall+0x6c/0xf8
>>> [ 3.208519] el0_svc_common.constprop.0+0x48/0xf0
>>> [ 3.211050] do_el0_svc+0x24/0x38
>>> [ 3.212990] el0_svc+0x164/0x3c8
>>> [ 3.214842] el0t_64_sync_handler+0xd0/0xe8
>>> [ 3.217251] el0t_64_sync+0x1b0/0x1b8
>>> [ 3.219450] hv_utils: Heartbeat IC version 3.0
>>> [ 3.219471] hv_utils: Shutdown IC version 3.2
>>> [ 3.219844] hv_utils: TimeSync IC version 4.0
>>
>> That matches with my expectation that the same problem exists on arm64.
>> The patch from Jan addresses that issue for x86 (only, so far) as we do
>> not have a working test environment for arm64 yet.
>
> OK. I had understood Jan's earlier comments to mean that the VMBus
> interrupt problem was implicitly solved on arm64 because of VMBus using
> a standard Linux IRQ on arm64. But evidently that's not the case. So my
> earlier comment stands: The code changes should go into the architecture
> independent portion of the VMBus driver, and not under arch/x86. I
> can probably work with you to test on arm64 if need be.
>
I can move the code, sure, but I still haven't understood what
invalidates my assumptions (beside what you observed). vmbus_drv calls
request_percpu_irq, and that is - as far as I can see - not injecting
IRQF_NO_THREAD. Any explanations welcome.
Reproduction is still not possible for me. I was playing a bit with qemu
in the hope to make it provide its minimal vmbus support (for
ballooning), but that was not yet successful on arm64.
Jan
--
Siemens AG, Foundational Technologies
Linux Expert Center
^ permalink raw reply
* Re: [PATCH 2/2] drm/hyperv: During panic do VMBus unload after frame buffer is flushed
From: Jocelyn Falempe @ 2026-02-12 10:10 UTC (permalink / raw)
To: mhklkml, mhklinux, drawat.floss, maarten.lankhorst, mripard,
tzimmermann, airlied, simona, kys, haiyangz, wei.liu, decui,
longli, ryasuoka
Cc: dri-devel, linux-kernel, linux-hyperv, stable
In-Reply-To: <e9d35c78-1c4b-4a9c-8cf0-9531e972279f@redhat.com>
On 12/02/2026 10:49, Jocelyn Falempe wrote:
> On 12/02/2026 00:01, mhklkml@zohomail.com wrote:
>> From: Jocelyn Falempe <jfalempe@redhat.com> Sent: Wednesday, February
>> 11, 2026 1:54 PM
>>
>> But for this patch, the issue is that drm_panic() never gets called if
>> CONFIG_PRINTK
>> isn't set. In that case, kmsg_dump_register() is a stub that returns
>> an error. So
>> drm_panic_register() never registers the callback to drm_panic(). And if
>> drm_panic() isn't going to run, responsibility for doing the VMBus unload
>> must remain with the VMBus code. It's hard to actually test this case
>> because
>> of depending on printk() for debugging output, so double-check my
>> thinking.
>
> Ok you're right. I changed from
> atomic_notifier_chain_register(&panic_notifier_list, ...) to
> kmsg_dump_register() in the v10 of drm_panic.
>
> So I should either make DRM_PANIC depends on PRINTK, or call
> atomic_notifier_chain_register() if PRINTK is not defined.
>
> As I think kernel without PRINTK are uncommon, I'll probably do the
> first solution.
>
FYI, I just sent the corresponding change:
https://patchwork.freedesktop.org/series/161544/
Best regards,
--
Jocelyn
^ permalink raw reply
* Re: [PATCH 2/2] drm/hyperv: During panic do VMBus unload after frame buffer is flushed
From: Jocelyn Falempe @ 2026-02-12 9:49 UTC (permalink / raw)
To: mhklkml, mhklinux, drawat.floss, maarten.lankhorst, mripard,
tzimmermann, airlied, simona, kys, haiyangz, wei.liu, decui,
longli, ryasuoka
Cc: dri-devel, linux-kernel, linux-hyperv, stable
In-Reply-To: <002601dc9baa$517d8b40$f478a1c0$@zohomail.com>
On 12/02/2026 00:01, mhklkml@zohomail.com wrote:
> From: Jocelyn Falempe <jfalempe@redhat.com> Sent: Wednesday, February 11, 2026 1:54 PM
>>
>> On 09/02/2026 08:02, mhkelley58@gmail.com wrote:
>>> From: Michael Kelley <mhklinux@outlook.com>
>>>
>>> In a VM, Linux panic information (reason for the panic, stack trace,
>>> etc.) may be written to a serial console and/or a virtual frame buffer
>>> for a graphics console. The latter may need to be flushed back to the
>>> host hypervisor for display.
>>>
>>> The current Hyper-V DRM driver for the frame buffer does the flushing
>>> *after* the VMBus connection has been unloaded, such that panic messages
>>> are not displayed on the graphics console. A user with a Hyper-V graphics
>>> console is left with just a hung empty screen after a panic. The enhanced
>>> control that DRM provides over the panic display in the graphics console
>>> is similarly non-functional.
>>>
>>> Commit 3671f3777758 ("drm/hyperv: Add support for drm_panic") added
>>> the Hyper-V DRM driver support to flush the virtual frame buffer. It
>>> provided necessary functionality but did not handle the sequencing
>>> problem with VMBus unload.
>>>
>>> Fix the full problem by using VMBus functions to suppress the VMBus
>>> unload that is normally done by the VMBus driver in the panic path. Then
>>> after the frame buffer has been flushed, do the VMBus unload so that a
>>> kdump kernel can start cleanly. As expected, CONFIG_DRM_PANIC must be
>>> selected for these changes to have effect. As a side benefit, the
>>> enhanced features of the DRM panic path are also functional.
>>
>> Thanks for properly fixing this issue with DRM Panic on hyperv.
>>
>> I've a small comment below.
>>
>> With that fixed:
>> Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
>>
>> The first patch looks good too, I can review it if no other step up, as
>> I'm not familiar with hyperv.
>>
>>>
>>> Fixes: 3671f3777758 ("drm/hyperv: Add support for drm_panic")
>>> Signed-off-by: Michael Kelley <mhklinux@outlook.com>
>>> ---
>>> drivers/gpu/drm/hyperv/hyperv_drm_drv.c | 4 ++++
>>> drivers/gpu/drm/hyperv/hyperv_drm_modeset.c | 15 ++++++++-------
>>> 2 files changed, 12 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
>> b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
>>> index 06b5d96e6eaf..79e51643be67 100644
>>> --- a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
>>> +++ b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
>>> @@ -150,6 +150,9 @@ static int hyperv_vmbus_probe(struct hv_device *hdev,
>>> goto err_free_mmio;
>>> }
>>>
>>> + /* If DRM panic path is stubbed out VMBus code must do the unload */
>>> + if (IS_ENABLED(CONFIG_DRM_PANIC) && IS_ENABLED(CONFIG_PRINTK))
>>
>> I think drm_panic should still work without printk.
>> The "user" panic screen would be unaffected, but the "kmsg" screen might
>> be blank, and the "qr_code" would generate an empty qr code.
>> (Actually I never tried to build a kernel without printk).
>
> Yeah, I had never built such a kernel either until recently when the kernel
> test robot flagged an error in Hyper-V code when CONFIG_PRINTK is not set. :-)
>
> But for this patch, the issue is that drm_panic() never gets called if CONFIG_PRINTK
> isn't set. In that case, kmsg_dump_register() is a stub that returns an error. So
> drm_panic_register() never registers the callback to drm_panic(). And if
> drm_panic() isn't going to run, responsibility for doing the VMBus unload
> must remain with the VMBus code. It's hard to actually test this case because
> of depending on printk() for debugging output, so double-check my
> thinking.
Ok you're right. I changed from
atomic_notifier_chain_register(&panic_notifier_list, ...) to
kmsg_dump_register() in the v10 of drm_panic.
So I should either make DRM_PANIC depends on PRINTK, or call
atomic_notifier_chain_register() if PRINTK is not defined.
As I think kernel without PRINTK are uncommon, I'll probably do the
first solution.
--
Jocelyn
>
> Michael
>
>>
>>> + vmbus_set_skip_unload(true);
>>> drm_client_setup(dev, NULL);
>>>
>>> return 0;
>
^ permalink raw reply
* Re: [RFC PATCH V2] x86/VMBus: Confidential VMBus for dynamic DMA buffer transition
From: Tianyu Lan @ 2026-02-12 8:26 UTC (permalink / raw)
To: Michael Kelley
Cc: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
decui@microsoft.com, longli@microsoft.com, Tianyu Lan,
linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
hch@infradead.org, robin.murphy@arm.com, vdso@hexbites.dev
In-Reply-To: <SN6PR02MB41577FB84EC73E48ABAC7D18D463A@SN6PR02MB4157.namprd02.prod.outlook.com>
On Thu, Feb 12, 2026 at 2:00 AM Michael Kelley <mhklinux@outlook.com> wrote:
>
> From: Tianyu Lan <ltykernel@gmail.com> Sent: Tuesday, February 10, 2026 8:21 AM
> >
> > Hyper-V provides Confidential VMBus to communicate between
> > device model and device guest driver via encrypted/private
> > memory in Confidential VM. The device model is in OpenHCL
> > (https://openvmm.dev/guide/user_guide/openhcl.html) that
> > plays the paravisor rule.
> >
> > For a VMBUS device, there are two communication methods to
>
> s/VMBUS/VMBus/
>
> > talk with Host/Hypervisor. 1) VMBus Ring buffer 2) dynamic
> > DMA transition.
>
> I'm not sure what "dynamic DMA transition" is. Maybe just
> "DMA transfers"? Also, do the same substitution further
> down in this commit message.
>
> > The Confidential VMBus Ring buffer has been
> > upstreamed by Roman Kisel(commit 6802d8af).
>
> It's customary to use 12 character commit IDs, which would be
> 6802d8af47d1 in this case.
>
> >
> > The dynamic DMA transition of VMBus device normally goes
> > through DMA core and it uses SWIOTLB as bounce buffer in
> > CVM
>
> "CVM" is Microsoft-speak. The Linux terminology is "a CoCo VM".
>
> > to communicate with Host/Hypervisor. The Confidential
> > VMBus device may use private/encrypted memory to do DMA
> > and so the device swiotlb(bounce buffer) isn't necessary.
>
> The phrase "isn't necessary" does not capture the real issue
> here. Saying "isn't necessary" makes it sound like this patch is
> just avoids unnecessary work, so that it is a performance
> improvement. But that's not the case.
>
> The real issue is that swiotlb memory is decrypted. So bouncing
> through the swiotlb exposes to the host what is supposed to be
> confidential data passed on the Confidential VMBus. Disabling
> the swiotlb bouncing in this case is a hard requirement to preserve
> confidentially.
>
> So I would reword the sentences as something like this:
>
> The Confidential VMBus device can do DMA directly to
> private/encrypted memory. Because the swiotlb is decrypted
> memory, the DMA transfer must not be bounced through the
> swiotlb, so as to preserve confidentiality. This is different from
> the default for Linux CoCo VMs, so disable the VMBus device's
> use of swiotlb.
>
> > To disable device's swiotlb, set device->dma_io_tlb_mem
> > to NULL in VMBus driver and is_swiotlb_force_bounce()
> > always returns false.
> >
> > Suggested-by: Michael Kelley <mhklinux@outlook.com>
> > Signed-off-by: Tianyu Lan <tiala@microsoft.com>
> > ---
> > Change since v1:
> > Use device.dma_io_tlb_mem to disable device bounce buffer
> >
> > drivers/hv/vmbus_drv.c | 6 +++++-
> > 1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> > index a53af6fe81a6..58dab8cc3fcb 100644
> > --- a/drivers/hv/vmbus_drv.c
> > +++ b/drivers/hv/vmbus_drv.c
> > @@ -2133,11 +2133,15 @@ int vmbus_device_register(struct hv_device *child_device_obj)
> > child_device_obj->device.dma_mask = &child_device_obj->dma_mask;
> > dma_set_mask(&child_device_obj->device, DMA_BIT_MASK(64));
> >
> > + device_initialize(&child_device_obj->device);
> > + if (child_device_obj->channel->co_external_memory)
> > + child_device_obj->device.dma_io_tlb_mem = NULL;
> > +
>
> Doing this as part of the VMBus bus driver makes sense. While directly
> setting device.dma_io_tlb_mem to NULL should work, it would be better
> to add a function to the swiotlb code to do this, and then call that function
> here, passing the device as an argument. The need to disable swiotlb on a
> device will likely arise in similar contexts (such as TDISP), and it would be
> better to have a swiotlb function for that purpose. This use case may be
> a bit ahead of the TDISP work, and having a swiotlb function in place will
> help ensure that duplicate mechanisms aren't created as everything
> comes together.
>
> See my earlier comments in [1] about the key point in the commit message,
> and about adding a swiotlb_dev_disable() function to the swiotlb code.
>
> Michael
Hi Michael:
Thanks for your review. Will add swiotlb_dev_disable() in the next version.
>
> [1] https://lore.kernel.org/linux-hyperv/SN6PR02MB4157DAE6D8CC6BA11CA87298D4DCA@SN6PR02MB4157.namprd02.prod.outlook.com/
>
> > /*
> > * Register with the LDM. This will kick off the driver/device
> > * binding...which will eventually call vmbus_match() and vmbus_probe()
> > */
> > - ret = device_register(&child_device_obj->device);
> > + ret = device_add(&child_device_obj->device);
> > if (ret) {
> > pr_err("Unable to register child device\n");
> > put_device(&child_device_obj->device);
> > --
> > 2.50.1
--
Thanks
Tianyu Lan
^ permalink raw reply
* Re: [PATCH 0/2] kexec: Refuse kernel-unsafe Microsoft Hypervisor transitions
From: Stanislav Kinsburskii @ 2026-02-11 23:30 UTC (permalink / raw)
To: rppt, akpm, bhe, kys, haiyangz, wei.liu, decui, longli
Cc: kexec, linux-hyperv, linux-kernel
In-Reply-To: <176962149772.85424.9395505307198316093.stgit@skinsburskii-cloud-desktop.internal.cloudapp.net>
On Wed, Jan 28, 2026 at 05:41:56PM +0000, Stanislav Kinsburskii wrote:
> When Microsoft Hypervisor is active, the kernel may have memory “deposited”
> to the hypervisor. Those pages are no longer safe for the kernel to touch,
> and attempting to access them can trigger a GPF. The problem becomes acute
> with kexec: the “deposited pages” state does not survive the transition,
> and the next kernel has no reliable way to know which pages are still
> owned/managed by the hypervisor.
>
> Until there is a proper handoff mechanism to preserve that state across
> kexec, the only safe behavior is to refuse kexec whenever there is shared
> hypervisor state that cannot survive the transition—most notably deposited
> pages, and also cases where VMs are still running.
>
> This series adds the missing kexec integration point needed by MSHV: a
> callback at the kexec “freeze” stage so the driver can make the transition
> safe (or block it). With this hook, MSHV can refuse kexec while VMs are
> running, attempt to withdraw deposited pages when possible (e.g. L1VH
> host), and fail the transition if any pages remain deposited.
>
> ---
>
> Stanislav Kinsburskii (2):
> kexec: Add permission notifier chain for kexec operations
> mshv: Add kexec blocking support
>
Hi,
I’m sending a gentle follow‑up on the patch series below, which I posted
about two weeks ago. I wanted to check whether anyone has had a chance
to look at it, or if there are concerns I should address.
Any feedback would be appreciated.
Thanks for your time.
Best regards,
Stanislav
>
> drivers/hv/Makefile | 1 +
> drivers/hv/hv_proc.c | 4 ++
> drivers/hv/mshv_kexec.c | 66 ++++++++++++++++++++++++++++++++++++++++
> drivers/hv/mshv_root.h | 14 ++++++++
> drivers/hv/mshv_root_hv_call.c | 2 +
> drivers/hv/mshv_root_main.c | 7 ++++
> include/linux/kexec.h | 6 ++++
> kernel/kexec_core.c | 24 +++++++++++++++
> 8 files changed, 124 insertions(+)
> create mode 100644 drivers/hv/mshv_kexec.c
>
^ permalink raw reply
* RE: [PATCH 2/2] drm/hyperv: During panic do VMBus unload after frame buffer is flushed
From: mhklkml @ 2026-02-11 23:01 UTC (permalink / raw)
To: 'Jocelyn Falempe', mhklinux, drawat.floss,
maarten.lankhorst, mripard, tzimmermann, airlied, simona, kys,
haiyangz, wei.liu, decui, longli, ryasuoka
Cc: dri-devel, linux-kernel, linux-hyperv, stable
In-Reply-To: <a5372b72-8dc0-4f2d-ad5c-086f3e75ee81@redhat.com>
From: Jocelyn Falempe <jfalempe@redhat.com> Sent: Wednesday, February 11, 2026 1:54 PM
>
> On 09/02/2026 08:02, mhkelley58@gmail.com wrote:
> > From: Michael Kelley <mhklinux@outlook.com>
> >
> > In a VM, Linux panic information (reason for the panic, stack trace,
> > etc.) may be written to a serial console and/or a virtual frame buffer
> > for a graphics console. The latter may need to be flushed back to the
> > host hypervisor for display.
> >
> > The current Hyper-V DRM driver for the frame buffer does the flushing
> > *after* the VMBus connection has been unloaded, such that panic messages
> > are not displayed on the graphics console. A user with a Hyper-V graphics
> > console is left with just a hung empty screen after a panic. The enhanced
> > control that DRM provides over the panic display in the graphics console
> > is similarly non-functional.
> >
> > Commit 3671f3777758 ("drm/hyperv: Add support for drm_panic") added
> > the Hyper-V DRM driver support to flush the virtual frame buffer. It
> > provided necessary functionality but did not handle the sequencing
> > problem with VMBus unload.
> >
> > Fix the full problem by using VMBus functions to suppress the VMBus
> > unload that is normally done by the VMBus driver in the panic path. Then
> > after the frame buffer has been flushed, do the VMBus unload so that a
> > kdump kernel can start cleanly. As expected, CONFIG_DRM_PANIC must be
> > selected for these changes to have effect. As a side benefit, the
> > enhanced features of the DRM panic path are also functional.
>
> Thanks for properly fixing this issue with DRM Panic on hyperv.
>
> I've a small comment below.
>
> With that fixed:
> Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
>
> The first patch looks good too, I can review it if no other step up, as
> I'm not familiar with hyperv.
>
> >
> > Fixes: 3671f3777758 ("drm/hyperv: Add support for drm_panic")
> > Signed-off-by: Michael Kelley <mhklinux@outlook.com>
> > ---
> > drivers/gpu/drm/hyperv/hyperv_drm_drv.c | 4 ++++
> > drivers/gpu/drm/hyperv/hyperv_drm_modeset.c | 15 ++++++++-------
> > 2 files changed, 12 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> > index 06b5d96e6eaf..79e51643be67 100644
> > --- a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> > +++ b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> > @@ -150,6 +150,9 @@ static int hyperv_vmbus_probe(struct hv_device *hdev,
> > goto err_free_mmio;
> > }
> >
> > + /* If DRM panic path is stubbed out VMBus code must do the unload */
> > + if (IS_ENABLED(CONFIG_DRM_PANIC) && IS_ENABLED(CONFIG_PRINTK))
>
> I think drm_panic should still work without printk.
> The "user" panic screen would be unaffected, but the "kmsg" screen might
> be blank, and the "qr_code" would generate an empty qr code.
> (Actually I never tried to build a kernel without printk).
Yeah, I had never built such a kernel either until recently when the kernel
test robot flagged an error in Hyper-V code when CONFIG_PRINTK is not set. :-)
But for this patch, the issue is that drm_panic() never gets called if CONFIG_PRINTK
isn't set. In that case, kmsg_dump_register() is a stub that returns an error. So
drm_panic_register() never registers the callback to drm_panic(). And if
drm_panic() isn't going to run, responsibility for doing the VMBus unload
must remain with the VMBus code. It's hard to actually test this case because
of depending on printk() for debugging output, so double-check my
thinking.
Michael
>
> > + vmbus_set_skip_unload(true);
> > drm_client_setup(dev, NULL);
> >
> > return 0;
^ permalink raw reply
* Re: [PATCH 2/2] drm/hyperv: During panic do VMBus unload after frame buffer is flushed
From: Jocelyn Falempe @ 2026-02-11 21:54 UTC (permalink / raw)
To: mhklinux, drawat.floss, maarten.lankhorst, mripard, tzimmermann,
airlied, simona, kys, haiyangz, wei.liu, decui, longli, ryasuoka
Cc: dri-devel, linux-kernel, linux-hyperv, stable
In-Reply-To: <20260209070201.1492-2-mhklinux@outlook.com>
On 09/02/2026 08:02, mhkelley58@gmail.com wrote:
> From: Michael Kelley <mhklinux@outlook.com>
>
> In a VM, Linux panic information (reason for the panic, stack trace,
> etc.) may be written to a serial console and/or a virtual frame buffer
> for a graphics console. The latter may need to be flushed back to the
> host hypervisor for display.
>
> The current Hyper-V DRM driver for the frame buffer does the flushing
> *after* the VMBus connection has been unloaded, such that panic messages
> are not displayed on the graphics console. A user with a Hyper-V graphics
> console is left with just a hung empty screen after a panic. The enhanced
> control that DRM provides over the panic display in the graphics console
> is similarly non-functional.
>
> Commit 3671f3777758 ("drm/hyperv: Add support for drm_panic") added
> the Hyper-V DRM driver support to flush the virtual frame buffer. It
> provided necessary functionality but did not handle the sequencing
> problem with VMBus unload.
>
> Fix the full problem by using VMBus functions to suppress the VMBus
> unload that is normally done by the VMBus driver in the panic path. Then
> after the frame buffer has been flushed, do the VMBus unload so that a
> kdump kernel can start cleanly. As expected, CONFIG_DRM_PANIC must be
> selected for these changes to have effect. As a side benefit, the
> enhanced features of the DRM panic path are also functional.
Thanks for properly fixing this issue with DRM Panic on hyperv.
I've a small comment below.
With that fixed:
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
The first patch looks good too, I can review it if no other step up, as
I'm not familiar with hyperv.
>
> Fixes: 3671f3777758 ("drm/hyperv: Add support for drm_panic")
> Signed-off-by: Michael Kelley <mhklinux@outlook.com>
> ---
> drivers/gpu/drm/hyperv/hyperv_drm_drv.c | 4 ++++
> drivers/gpu/drm/hyperv/hyperv_drm_modeset.c | 15 ++++++++-------
> 2 files changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> index 06b5d96e6eaf..79e51643be67 100644
> --- a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> +++ b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> @@ -150,6 +150,9 @@ static int hyperv_vmbus_probe(struct hv_device *hdev,
> goto err_free_mmio;
> }
>
> + /* If DRM panic path is stubbed out VMBus code must do the unload */
> + if (IS_ENABLED(CONFIG_DRM_PANIC) && IS_ENABLED(CONFIG_PRINTK))
I think drm_panic should still work without printk.
The "user" panic screen would be unaffected, but the "kmsg" screen might
be blank, and the "qr_code" would generate an empty qr code.
(Actually I never tried to build a kernel without printk).
> + vmbus_set_skip_unload(true);
> drm_client_setup(dev, NULL);
>
> return 0;
> @@ -169,6 +172,7 @@ static void hyperv_vmbus_remove(struct hv_device *hdev)
> struct drm_device *dev = hv_get_drvdata(hdev);
> struct hyperv_drm_device *hv = to_hv(dev);
>
> + vmbus_set_skip_unload(false);
> drm_dev_unplug(dev);
> drm_atomic_helper_shutdown(dev);
> vmbus_close(hdev->channel);
> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> index 7978f8c8108c..d48ca6c23b7c 100644
> --- a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> +++ b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> @@ -212,15 +212,16 @@ static void hyperv_plane_panic_flush(struct drm_plane *plane)
> struct hyperv_drm_device *hv = to_hv(plane->dev);
> struct drm_rect rect;
>
> - if (!plane->state || !plane->state->fb)
> - return;
> + if (plane->state && plane->state->fb) {
> + rect.x1 = 0;
> + rect.y1 = 0;
> + rect.x2 = plane->state->fb->width;
> + rect.y2 = plane->state->fb->height;
>
> - rect.x1 = 0;
> - rect.y1 = 0;
> - rect.x2 = plane->state->fb->width;
> - rect.y2 = plane->state->fb->height;
> + hyperv_update_dirt(hv->hdev, &rect);
> + }
>
> - hyperv_update_dirt(hv->hdev, &rect);
> + vmbus_initiate_unload(true);
> }
>
> static const struct drm_plane_helper_funcs hyperv_plane_helper_funcs = {
--
Jocelyn
^ permalink raw reply
* Re: [RFC PATCH V2] x86/VMBus: Confidential VMBus for dynamic DMA buffer transition
From: Robin Murphy @ 2026-02-11 19:51 UTC (permalink / raw)
To: Michael Kelley, Tianyu Lan, kys@microsoft.com,
haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com,
longli@microsoft.com
Cc: Tianyu Lan, linux-hyperv@vger.kernel.org,
linux-kernel@vger.kernel.org, hch@infradead.org,
vdso@hexbites.dev, Suzuki K Poulose, Aneesh Kumar K.V (Arm)
In-Reply-To: <SN6PR02MB41577FB84EC73E48ABAC7D18D463A@SN6PR02MB4157.namprd02.prod.outlook.com>
On 2026-02-11 6:00 pm, Michael Kelley wrote:
> From: Tianyu Lan <ltykernel@gmail.com> Sent: Tuesday, February 10, 2026 8:21 AM
>>
>> Hyper-V provides Confidential VMBus to communicate between
>> device model and device guest driver via encrypted/private
>> memory in Confidential VM. The device model is in OpenHCL
>> (https://openvmm.dev/guide/user_guide/openhcl.html) that
>> plays the paravisor rule.
>>
>> For a VMBUS device, there are two communication methods to
>
> s/VMBUS/VMBus/
>
>> talk with Host/Hypervisor. 1) VMBus Ring buffer 2) dynamic
>> DMA transition.
>
> I'm not sure what "dynamic DMA transition" is. Maybe just
> "DMA transfers"? Also, do the same substitution further
> down in this commit message.
>
>> The Confidential VMBus Ring buffer has been
>> upstreamed by Roman Kisel(commit 6802d8af).
>
> It's customary to use 12 character commit IDs, which would be
> 6802d8af47d1 in this case.
>
>>
>> The dynamic DMA transition of VMBus device normally goes
>> through DMA core and it uses SWIOTLB as bounce buffer in
>> CVM
>
> "CVM" is Microsoft-speak. The Linux terminology is "a CoCo VM".
>
>> to communicate with Host/Hypervisor. The Confidential
>> VMBus device may use private/encrypted memory to do DMA
>> and so the device swiotlb(bounce buffer) isn't necessary.
>
> The phrase "isn't necessary" does not capture the real issue
> here. Saying "isn't necessary" makes it sound like this patch is
> just avoids unnecessary work, so that it is a performance
> improvement. But that's not the case.
>
> The real issue is that swiotlb memory is decrypted. So bouncing
> through the swiotlb exposes to the host what is supposed to be
> confidential data passed on the Confidential VMBus. Disabling
> the swiotlb bouncing in this case is a hard requirement to preserve
> confidentially.
Yeah, this really isn't a Hyper-V problem. Indeed as things stand,
"swiotlb=force" could potentially break confidentiality for any
environment trying to invent a notion of private DMA, and perhaps we
could throw a big warning about that, but really the answer there is
"Don't run your confidential workload with 'swiotlb=force'. Why would
you even do that? Debug your drivers in a regular VM or bare-metal with
full debug visibility like a normal person..."
The fact is we do not have a proper notion of trusted/private DMA yet,
and this is not the way to add it. The current assumption is very much
that all DMA is untrusted in the CoCo sense, because initially it was
only virtual devices emulated by a hypervisor, thus had to be bounced
through shared memory anyway. AMD SEV with a stage 1 IOMMU in the guest
can allow an assigned physical device to access a suitably-aligned
encrypted buffer directly, but that's still effectively just putting the
buffer into a temporarily shared state for that device, it merely skips
sharing it with the rest of the system. !force_dma_unencrypted() doesn't
mean "we trust this device's DMA", it just means "we don't have to use
explicitly-decrypted pages to accommodate untrusted/shared DMA here",
plus it also serves double-duty for host encryption which doesn't share
the same trust model anyway.
I assumed this would follow the TDISP stuff, but if Hyper-V has an
alternative device-trusting mechanism already then there's no need to
wait. We want some common device property (likely consolidating the
current PCI external-facing port notion of trustedness plus whatever
TDISP wants), with which we can then make proper decisions in all the
right DMA API paths - and if it can end up replacing the horrible
force_dma_unencrypted() as well then all the better! I'd totally
forgotten about the previous discussion that Michael referred to (which
I had to track down[1]), but it looks like all the main points were
already covered there and we were approaching a consensus, so really I
guess someone just needs to give it a go.
Thanks,
Robin.
[1]
https://lore.kernel.org/linux-hyperv/20250409000835.285105-6-romank@linux.microsoft.com/
>
> So I would reword the sentences as something like this:
>
> The Confidential VMBus device can do DMA directly to
> private/encrypted memory. Because the swiotlb is decrypted
> memory, the DMA transfer must not be bounced through the
> swiotlb, so as to preserve confidentiality. This is different from
> the default for Linux CoCo VMs, so disable the VMBus device's
> use of swiotlb.
>
>> To disable device's swiotlb, set device->dma_io_tlb_mem
>> to NULL in VMBus driver and is_swiotlb_force_bounce()
>> always returns false.
>>
>> Suggested-by: Michael Kelley <mhklinux@outlook.com>
>> Signed-off-by: Tianyu Lan <tiala@microsoft.com>
>> ---
>> Change since v1:
>> Use device.dma_io_tlb_mem to disable device bounce buffer
>>
>> drivers/hv/vmbus_drv.c | 6 +++++-
>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
>> index a53af6fe81a6..58dab8cc3fcb 100644
>> --- a/drivers/hv/vmbus_drv.c
>> +++ b/drivers/hv/vmbus_drv.c
>> @@ -2133,11 +2133,15 @@ int vmbus_device_register(struct hv_device *child_device_obj)
>> child_device_obj->device.dma_mask = &child_device_obj->dma_mask;
>> dma_set_mask(&child_device_obj->device, DMA_BIT_MASK(64));
>>
>> + device_initialize(&child_device_obj->device);
>> + if (child_device_obj->channel->co_external_memory)
>> + child_device_obj->device.dma_io_tlb_mem = NULL;
>> +
>
> Doing this as part of the VMBus bus driver makes sense. While directly
> setting device.dma_io_tlb_mem to NULL should work, it would be better
> to add a function to the swiotlb code to do this, and then call that function
> here, passing the device as an argument. The need to disable swiotlb on a
> device will likely arise in similar contexts (such as TDISP), and it would be
> better to have a swiotlb function for that purpose. This use case may be
> a bit ahead of the TDISP work, and having a swiotlb function in place will
> help ensure that duplicate mechanisms aren't created as everything
> comes together.
>
> See my earlier comments in [1] about the key point in the commit message,
> and about adding a swiotlb_dev_disable() function to the swiotlb code.
>
> Michael
>
> [1] https://lore.kernel.org/linux-hyperv/SN6PR02MB4157DAE6D8CC6BA11CA87298D4DCA@SN6PR02MB4157.namprd02.prod.outlook.com/
>
>> /*
>> * Register with the LDM. This will kick off the driver/device
>> * binding...which will eventually call vmbus_match() and vmbus_probe()
>> */
>> - ret = device_register(&child_device_obj->device);
>> + ret = device_add(&child_device_obj->device);
>> if (ret) {
>> pr_err("Unable to register child device\n");
>> put_device(&child_device_obj->device);
>> --
>> 2.50.1
^ permalink raw reply
* Re: [PATCH net-next v3] net: mana: Add MAC address to vPort logs and clarify error messages
From: Jakub Kicinski @ 2026-02-11 18:42 UTC (permalink / raw)
To: Erni Sri Satya Vennela
Cc: ernis, kys, haiyangz, wei.liu, decui, longli, andrew+netdev,
davem, edumazet, pabeni, dipayanroy, shradhagupta, shirazsaleem,
gargaditya, linux-hyperv, netdev, linux-kernel
In-Reply-To: <20260211054335.8511-1-ernis@linux.microsoft.com>
On Tue, 10 Feb 2026 21:43:24 -0800 Erni Sri Satya Vennela wrote:
> Add MAC address to vPort configuration success message and update error
> message to be more specific about HWC message errors in
> mana_send_request and mana_hwc_send_request.
## Form letter - net-next-closed
We have already submitted our pull request with net-next material for v7.0,
and therefore net-next is closed for new drivers, features, code refactoring
and optimizations. We are currently accepting bug fixes only.
Please repost when net-next reopens after Feb 23rd.
RFC patches sent for review only are obviously welcome at any time.
See: https://www.kernel.org/doc/html/next/process/maintainer-netdev.html#development-cycle
--
pw-bot: defer
pv-bot: closed
^ permalink raw reply
* RE: [RFC PATCH V2] x86/VMBus: Confidential VMBus for dynamic DMA buffer transition
From: Michael Kelley @ 2026-02-11 18:00 UTC (permalink / raw)
To: Tianyu Lan, kys@microsoft.com, haiyangz@microsoft.com,
wei.liu@kernel.org, decui@microsoft.com, longli@microsoft.com
Cc: Tianyu Lan, linux-hyperv@vger.kernel.org,
linux-kernel@vger.kernel.org, hch@infradead.org,
robin.murphy@arm.com, vdso@hexbites.dev
In-Reply-To: <20260210162107.2270823-1-ltykernel@gmail.com>
From: Tianyu Lan <ltykernel@gmail.com> Sent: Tuesday, February 10, 2026 8:21 AM
>
> Hyper-V provides Confidential VMBus to communicate between
> device model and device guest driver via encrypted/private
> memory in Confidential VM. The device model is in OpenHCL
> (https://openvmm.dev/guide/user_guide/openhcl.html) that
> plays the paravisor rule.
>
> For a VMBUS device, there are two communication methods to
s/VMBUS/VMBus/
> talk with Host/Hypervisor. 1) VMBus Ring buffer 2) dynamic
> DMA transition.
I'm not sure what "dynamic DMA transition" is. Maybe just
"DMA transfers"? Also, do the same substitution further
down in this commit message.
> The Confidential VMBus Ring buffer has been
> upstreamed by Roman Kisel(commit 6802d8af).
It's customary to use 12 character commit IDs, which would be
6802d8af47d1 in this case.
>
> The dynamic DMA transition of VMBus device normally goes
> through DMA core and it uses SWIOTLB as bounce buffer in
> CVM
"CVM" is Microsoft-speak. The Linux terminology is "a CoCo VM".
> to communicate with Host/Hypervisor. The Confidential
> VMBus device may use private/encrypted memory to do DMA
> and so the device swiotlb(bounce buffer) isn't necessary.
The phrase "isn't necessary" does not capture the real issue
here. Saying "isn't necessary" makes it sound like this patch is
just avoids unnecessary work, so that it is a performance
improvement. But that's not the case.
The real issue is that swiotlb memory is decrypted. So bouncing
through the swiotlb exposes to the host what is supposed to be
confidential data passed on the Confidential VMBus. Disabling
the swiotlb bouncing in this case is a hard requirement to preserve
confidentially.
So I would reword the sentences as something like this:
The Confidential VMBus device can do DMA directly to
private/encrypted memory. Because the swiotlb is decrypted
memory, the DMA transfer must not be bounced through the
swiotlb, so as to preserve confidentiality. This is different from
the default for Linux CoCo VMs, so disable the VMBus device's
use of swiotlb.
> To disable device's swiotlb, set device->dma_io_tlb_mem
> to NULL in VMBus driver and is_swiotlb_force_bounce()
> always returns false.
>
> Suggested-by: Michael Kelley <mhklinux@outlook.com>
> Signed-off-by: Tianyu Lan <tiala@microsoft.com>
> ---
> Change since v1:
> Use device.dma_io_tlb_mem to disable device bounce buffer
>
> drivers/hv/vmbus_drv.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index a53af6fe81a6..58dab8cc3fcb 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -2133,11 +2133,15 @@ int vmbus_device_register(struct hv_device *child_device_obj)
> child_device_obj->device.dma_mask = &child_device_obj->dma_mask;
> dma_set_mask(&child_device_obj->device, DMA_BIT_MASK(64));
>
> + device_initialize(&child_device_obj->device);
> + if (child_device_obj->channel->co_external_memory)
> + child_device_obj->device.dma_io_tlb_mem = NULL;
> +
Doing this as part of the VMBus bus driver makes sense. While directly
setting device.dma_io_tlb_mem to NULL should work, it would be better
to add a function to the swiotlb code to do this, and then call that function
here, passing the device as an argument. The need to disable swiotlb on a
device will likely arise in similar contexts (such as TDISP), and it would be
better to have a swiotlb function for that purpose. This use case may be
a bit ahead of the TDISP work, and having a swiotlb function in place will
help ensure that duplicate mechanisms aren't created as everything
comes together.
See my earlier comments in [1] about the key point in the commit message,
and about adding a swiotlb_dev_disable() function to the swiotlb code.
Michael
[1] https://lore.kernel.org/linux-hyperv/SN6PR02MB4157DAE6D8CC6BA11CA87298D4DCA@SN6PR02MB4157.namprd02.prod.outlook.com/
> /*
> * Register with the LDM. This will kick off the driver/device
> * binding...which will eventually call vmbus_match() and vmbus_probe()
> */
> - ret = device_register(&child_device_obj->device);
> + ret = device_add(&child_device_obj->device);
> if (ret) {
> pr_err("Unable to register child device\n");
> put_device(&child_device_obj->device);
> --
> 2.50.1
^ permalink raw reply
* [PATCH v4 2/2] mshv: add arm64 support for doorbell & intercept SINTs
From: Anirudh Rayabharam @ 2026-02-11 17:07 UTC (permalink / raw)
To: kys, haiyangz, wei.liu, decui, longli, linux-hyperv, linux-kernel; +Cc: anirudh
In-Reply-To: <20260211170728.3056226-1-anirudh@anirudhrb.com>
From: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
On x86, the HYPERVISOR_CALLBACK_VECTOR is used to receive synthetic
interrupts (SINTs) from the hypervisor for doorbells and intercepts.
There is no such vector reserved for arm64.
On arm64, the hypervisor exposes a synthetic register that can be read
to find the INTID that should be used for SINTs. This INTID is in the
PPI range.
To better unify the code paths, introduce mshv_sint_vector_init() that
either reads the synthetic register and obtains the INTID (arm64) or
just uses HYPERVISOR_CALLBACK_VECTOR as the interrupt vector (x86).
Signed-off-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
---
drivers/hv/mshv_synic.c | 112 +++++++++++++++++++++++++++++++++---
include/hyperv/hvgdk_mini.h | 2 +
2 files changed, 107 insertions(+), 7 deletions(-)
diff --git a/drivers/hv/mshv_synic.c b/drivers/hv/mshv_synic.c
index 074e37c48876..7957ad0328dd 100644
--- a/drivers/hv/mshv_synic.c
+++ b/drivers/hv/mshv_synic.c
@@ -10,17 +10,24 @@
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.h>
+#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/random.h>
#include <linux/cpuhotplug.h>
#include <linux/reboot.h>
#include <asm/mshyperv.h>
+#include <linux/platform_device.h>
+#include <linux/acpi.h>
#include "mshv_eventfd.h"
#include "mshv.h"
static int synic_cpuhp_online;
static struct hv_synic_pages __percpu *synic_pages;
+static int mshv_sint_vector = -1; /* hwirq for the SynIC SINTs */
+#ifndef HYPERVISOR_CALLBACK_VECTOR
+static int mshv_sint_irq = -1; /* Linux IRQ for mshv_sint_vector */
+#endif
static u32 synic_event_ring_get_queued_port(u32 sint_index)
{
@@ -456,9 +463,7 @@ static int mshv_synic_cpu_init(unsigned int cpu)
union hv_synic_simp simp;
union hv_synic_siefp siefp;
union hv_synic_sirbp sirbp;
-#ifdef HYPERVISOR_CALLBACK_VECTOR
union hv_synic_sint sint;
-#endif
union hv_synic_scontrol sctrl;
struct hv_synic_pages *spages = this_cpu_ptr(synic_pages);
struct hv_message_page **msg_page = &spages->hyp_synic_message_page;
@@ -501,10 +506,13 @@ static int mshv_synic_cpu_init(unsigned int cpu)
hv_set_non_nested_msr(HV_MSR_SIRBP, sirbp.as_uint64);
-#ifdef HYPERVISOR_CALLBACK_VECTOR
+#ifndef HYPERVISOR_CALLBACK_VECTOR
+ enable_percpu_irq(mshv_sint_irq, 0);
+#endif
+
/* Enable intercepts */
sint.as_uint64 = 0;
- sint.vector = HYPERVISOR_CALLBACK_VECTOR;
+ sint.vector = mshv_sint_vector;
sint.masked = false;
sint.auto_eoi = hv_recommend_using_aeoi();
hv_set_non_nested_msr(HV_MSR_SINT0 + HV_SYNIC_INTERCEPTION_SINT_INDEX,
@@ -512,13 +520,12 @@ static int mshv_synic_cpu_init(unsigned int cpu)
/* Doorbell SINT */
sint.as_uint64 = 0;
- sint.vector = HYPERVISOR_CALLBACK_VECTOR;
+ sint.vector = mshv_sint_vector;
sint.masked = false;
sint.as_intercept = 1;
sint.auto_eoi = hv_recommend_using_aeoi();
hv_set_non_nested_msr(HV_MSR_SINT0 + HV_SYNIC_DOORBELL_SINT_INDEX,
sint.as_uint64);
-#endif
/* Enable global synic bit */
sctrl.as_uint64 = hv_get_non_nested_msr(HV_MSR_SCONTROL);
@@ -573,6 +580,10 @@ static int mshv_synic_cpu_exit(unsigned int cpu)
hv_set_non_nested_msr(HV_MSR_SINT0 + HV_SYNIC_DOORBELL_SINT_INDEX,
sint.as_uint64);
+#ifndef HYPERVISOR_CALLBACK_VECTOR
+ disable_percpu_irq(mshv_sint_irq);
+#endif
+
/* Disable Synic's event ring page */
sirbp.as_uint64 = hv_get_non_nested_msr(HV_MSR_SIRBP);
sirbp.sirbp_enabled = false;
@@ -683,14 +694,98 @@ static struct notifier_block mshv_synic_reboot_nb = {
.notifier_call = mshv_synic_reboot_notify,
};
+#ifndef HYPERVISOR_CALLBACK_VECTOR
+#ifdef CONFIG_ACPI
+static long __percpu *mshv_evt;
+#endif
+
+static irqreturn_t mshv_percpu_isr(int irq, void *dev_id)
+{
+ mshv_isr();
+ return IRQ_HANDLED;
+}
+
+static int __init mshv_sint_vector_init(void)
+{
+#ifdef CONFIG_ACPI
+ int ret;
+ struct hv_register_assoc reg = {
+ .name = HV_ARM64_REGISTER_SINT_RESERVED_INTERRUPT_ID,
+ };
+ union hv_input_vtl input_vtl = { 0 };
+
+ ret = hv_call_get_vp_registers(HV_VP_INDEX_SELF, HV_PARTITION_ID_SELF,
+ 1, input_vtl, ®);
+ if (ret || !reg.value.reg64)
+ return -ENODEV;
+
+ mshv_sint_vector = reg.value.reg64;
+ ret = acpi_register_gsi(NULL, mshv_sint_vector, ACPI_EDGE_SENSITIVE,
+ ACPI_ACTIVE_HIGH);
+ if (ret < 0)
+ goto out_fail;
+
+ mshv_sint_irq = ret;
+
+ mshv_evt = alloc_percpu(long);
+ if (!mshv_evt) {
+ ret = -ENOMEM;
+ goto out_unregister;
+ }
+
+ ret = request_percpu_irq(mshv_sint_irq, mshv_percpu_isr, "MSHV",
+ mshv_evt);
+ if (ret)
+ goto free_evt;
+
+ return 0;
+
+free_evt:
+ free_percpu(mshv_evt);
+out_unregister:
+ acpi_unregister_gsi(mshv_sint_vector);
+out_fail:
+ return ret;
+#else
+ return -ENODEV;
+#endif
+}
+
+static void mshv_sint_vector_cleanup(void)
+{
+#ifdef CONFIG_ACPI
+ free_percpu_irq(mshv_sint_irq, mshv_evt);
+ free_percpu(mshv_evt);
+ acpi_unregister_gsi(mshv_sint_vector);
+#endif
+}
+#else /* !HYPERVISOR_CALLBACK_VECTOR */
+static int __init mshv_sint_vector_init(void)
+{
+ mshv_sint_vector = HYPERVISOR_CALLBACK_VECTOR;
+ return 0;
+}
+
+static void mshv_sint_vector_cleanup(void)
+{
+}
+#endif /* HYPERVISOR_CALLBACK_VECTOR */
+
int __init mshv_synic_init(struct device *dev)
{
int ret = 0;
+ ret = mshv_sint_vector_init();
+ if (ret) {
+ dev_err(dev, "Failed to get MSHV SINT vector: %i\n", ret);
+ return ret;
+ }
+
synic_pages = alloc_percpu(struct hv_synic_pages);
if (!synic_pages) {
dev_err(dev, "Failed to allocate percpu synic page\n");
- return -ENOMEM;
+ ret = -ENOMEM;
+ goto sint_vector_cleanup;
}
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mshv_synic",
@@ -713,6 +808,8 @@ int __init mshv_synic_init(struct device *dev)
cpuhp_remove_state(synic_cpuhp_online);
free_synic_pages:
free_percpu(synic_pages);
+sint_vector_cleanup:
+ mshv_sint_vector_cleanup();
return ret;
}
@@ -721,4 +818,5 @@ void mshv_synic_cleanup(void)
unregister_reboot_notifier(&mshv_synic_reboot_nb);
cpuhp_remove_state(synic_cpuhp_online);
free_percpu(synic_pages);
+ mshv_sint_vector_cleanup();
}
diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
index 30fbbde81c5c..7676f78e0766 100644
--- a/include/hyperv/hvgdk_mini.h
+++ b/include/hyperv/hvgdk_mini.h
@@ -1117,6 +1117,8 @@ enum hv_register_name {
HV_X64_REGISTER_MSR_MTRR_FIX4KF8000 = 0x0008007A,
HV_X64_REGISTER_REG_PAGE = 0x0009001C,
+#elif defined(CONFIG_ARM64)
+ HV_ARM64_REGISTER_SINT_RESERVED_INTERRUPT_ID = 0x00070001,
#endif
};
--
2.34.1
^ permalink raw reply related
* [PATCH v4 1/2] mshv: refactor synic init and cleanup
From: Anirudh Rayabharam @ 2026-02-11 17:07 UTC (permalink / raw)
To: kys, haiyangz, wei.liu, decui, longli, linux-hyperv, linux-kernel; +Cc: anirudh
In-Reply-To: <20260211170728.3056226-1-anirudh@anirudhrb.com>
From: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Rename mshv_synic_init() to mshv_synic_cpu_init() and
mshv_synic_cleanup() to mshv_synic_cpu_exit() to better reflect that
these functions handle per-cpu synic setup and teardown.
Use mshv_synic_init/cleanup() to perform init/cleanup that is not per-cpu.
Move all the synic related setup from mshv_parent_partition_init.
Move the reboot notifier to mshv_synic.c because it currently only
operates on the synic cpuhp state.
Move out synic_pages from the global mshv_root since it's use is now
completely local to mshv_synic.c.
This is in preparation for the next patch which will add more stuff to
mshv_synic_init().
No functional change.
Signed-off-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
---
drivers/hv/mshv_root.h | 5 ++-
drivers/hv/mshv_root_main.c | 59 +++++-------------------------
drivers/hv/mshv_synic.c | 71 +++++++++++++++++++++++++++++++++----
3 files changed, 75 insertions(+), 60 deletions(-)
diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
index 3c1d88b36741..26e0320c8097 100644
--- a/drivers/hv/mshv_root.h
+++ b/drivers/hv/mshv_root.h
@@ -183,7 +183,6 @@ struct hv_synic_pages {
};
struct mshv_root {
- struct hv_synic_pages __percpu *synic_pages;
spinlock_t pt_ht_lock;
DECLARE_HASHTABLE(pt_htable, MSHV_PARTITIONS_HASH_BITS);
struct hv_partition_property_vmm_capabilities vmm_caps;
@@ -242,8 +241,8 @@ int mshv_register_doorbell(u64 partition_id, doorbell_cb_t doorbell_cb,
void mshv_unregister_doorbell(u64 partition_id, int doorbell_portid);
void mshv_isr(void);
-int mshv_synic_init(unsigned int cpu);
-int mshv_synic_cleanup(unsigned int cpu);
+int mshv_synic_init(struct device *dev);
+void mshv_synic_cleanup(void);
static inline bool mshv_partition_encrypted(struct mshv_partition *partition)
{
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index 681b58154d5e..7c1666456e78 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -2035,7 +2035,6 @@ mshv_dev_release(struct inode *inode, struct file *filp)
return 0;
}
-static int mshv_cpuhp_online;
static int mshv_root_sched_online;
static const char *scheduler_type_to_string(enum hv_scheduler_type type)
@@ -2198,40 +2197,14 @@ root_scheduler_deinit(void)
free_percpu(root_scheduler_output);
}
-static int mshv_reboot_notify(struct notifier_block *nb,
- unsigned long code, void *unused)
-{
- cpuhp_remove_state(mshv_cpuhp_online);
- return 0;
-}
-
-struct notifier_block mshv_reboot_nb = {
- .notifier_call = mshv_reboot_notify,
-};
-
static void mshv_root_partition_exit(void)
{
- unregister_reboot_notifier(&mshv_reboot_nb);
root_scheduler_deinit();
}
static int __init mshv_root_partition_init(struct device *dev)
{
- int err;
-
- err = root_scheduler_init(dev);
- if (err)
- return err;
-
- err = register_reboot_notifier(&mshv_reboot_nb);
- if (err)
- goto root_sched_deinit;
-
- return 0;
-
-root_sched_deinit:
- root_scheduler_deinit();
- return err;
+ return root_scheduler_init(dev);
}
static void mshv_init_vmm_caps(struct device *dev)
@@ -2276,31 +2249,18 @@ static int __init mshv_parent_partition_init(void)
MSHV_HV_MAX_VERSION);
}
- mshv_root.synic_pages = alloc_percpu(struct hv_synic_pages);
- if (!mshv_root.synic_pages) {
- dev_err(dev, "Failed to allocate percpu synic page\n");
- ret = -ENOMEM;
+ ret = mshv_synic_init(dev);
+ if (ret)
goto device_deregister;
- }
-
- ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mshv_synic",
- mshv_synic_init,
- mshv_synic_cleanup);
- if (ret < 0) {
- dev_err(dev, "Failed to setup cpu hotplug state: %i\n", ret);
- goto free_synic_pages;
- }
-
- mshv_cpuhp_online = ret;
ret = mshv_retrieve_scheduler_type(dev);
if (ret)
- goto remove_cpu_state;
+ goto synic_cleanup;
if (hv_root_partition())
ret = mshv_root_partition_init(dev);
if (ret)
- goto remove_cpu_state;
+ goto synic_cleanup;
mshv_init_vmm_caps(dev);
@@ -2318,10 +2278,8 @@ static int __init mshv_parent_partition_init(void)
exit_partition:
if (hv_root_partition())
mshv_root_partition_exit();
-remove_cpu_state:
- cpuhp_remove_state(mshv_cpuhp_online);
-free_synic_pages:
- free_percpu(mshv_root.synic_pages);
+synic_cleanup:
+ mshv_synic_cleanup();
device_deregister:
misc_deregister(&mshv_dev);
return ret;
@@ -2335,8 +2293,7 @@ static void __exit mshv_parent_partition_exit(void)
mshv_irqfd_wq_cleanup();
if (hv_root_partition())
mshv_root_partition_exit();
- cpuhp_remove_state(mshv_cpuhp_online);
- free_percpu(mshv_root.synic_pages);
+ mshv_synic_cleanup();
}
module_init(mshv_parent_partition_init);
diff --git a/drivers/hv/mshv_synic.c b/drivers/hv/mshv_synic.c
index f8b0337cdc82..074e37c48876 100644
--- a/drivers/hv/mshv_synic.c
+++ b/drivers/hv/mshv_synic.c
@@ -12,11 +12,16 @@
#include <linux/mm.h>
#include <linux/io.h>
#include <linux/random.h>
+#include <linux/cpuhotplug.h>
+#include <linux/reboot.h>
#include <asm/mshyperv.h>
#include "mshv_eventfd.h"
#include "mshv.h"
+static int synic_cpuhp_online;
+static struct hv_synic_pages __percpu *synic_pages;
+
static u32 synic_event_ring_get_queued_port(u32 sint_index)
{
struct hv_synic_event_ring_page **event_ring_page;
@@ -26,7 +31,7 @@ static u32 synic_event_ring_get_queued_port(u32 sint_index)
u32 message;
u8 tail;
- spages = this_cpu_ptr(mshv_root.synic_pages);
+ spages = this_cpu_ptr(synic_pages);
event_ring_page = &spages->synic_event_ring_page;
synic_eventring_tail = (u8 **)this_cpu_ptr(hv_synic_eventring_tail);
@@ -393,7 +398,7 @@ mshv_intercept_isr(struct hv_message *msg)
void mshv_isr(void)
{
- struct hv_synic_pages *spages = this_cpu_ptr(mshv_root.synic_pages);
+ struct hv_synic_pages *spages = this_cpu_ptr(synic_pages);
struct hv_message_page **msg_page = &spages->hyp_synic_message_page;
struct hv_message *msg;
bool handled;
@@ -446,7 +451,7 @@ void mshv_isr(void)
}
}
-int mshv_synic_init(unsigned int cpu)
+static int mshv_synic_cpu_init(unsigned int cpu)
{
union hv_synic_simp simp;
union hv_synic_siefp siefp;
@@ -455,7 +460,7 @@ int mshv_synic_init(unsigned int cpu)
union hv_synic_sint sint;
#endif
union hv_synic_scontrol sctrl;
- struct hv_synic_pages *spages = this_cpu_ptr(mshv_root.synic_pages);
+ struct hv_synic_pages *spages = this_cpu_ptr(synic_pages);
struct hv_message_page **msg_page = &spages->hyp_synic_message_page;
struct hv_synic_event_flags_page **event_flags_page =
&spages->synic_event_flags_page;
@@ -542,14 +547,14 @@ int mshv_synic_init(unsigned int cpu)
return -EFAULT;
}
-int mshv_synic_cleanup(unsigned int cpu)
+static int mshv_synic_cpu_exit(unsigned int cpu)
{
union hv_synic_sint sint;
union hv_synic_simp simp;
union hv_synic_siefp siefp;
union hv_synic_sirbp sirbp;
union hv_synic_scontrol sctrl;
- struct hv_synic_pages *spages = this_cpu_ptr(mshv_root.synic_pages);
+ struct hv_synic_pages *spages = this_cpu_ptr(synic_pages);
struct hv_message_page **msg_page = &spages->hyp_synic_message_page;
struct hv_synic_event_flags_page **event_flags_page =
&spages->synic_event_flags_page;
@@ -663,3 +668,57 @@ mshv_unregister_doorbell(u64 partition_id, int doorbell_portid)
mshv_portid_free(doorbell_portid);
}
+
+static int mshv_synic_reboot_notify(struct notifier_block *nb,
+ unsigned long code, void *unused)
+{
+ if (!hv_root_partition())
+ return 0;
+
+ cpuhp_remove_state(synic_cpuhp_online);
+ return 0;
+}
+
+static struct notifier_block mshv_synic_reboot_nb = {
+ .notifier_call = mshv_synic_reboot_notify,
+};
+
+int __init mshv_synic_init(struct device *dev)
+{
+ int ret = 0;
+
+ synic_pages = alloc_percpu(struct hv_synic_pages);
+ if (!synic_pages) {
+ dev_err(dev, "Failed to allocate percpu synic page\n");
+ return -ENOMEM;
+ }
+
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mshv_synic",
+ mshv_synic_cpu_init,
+ mshv_synic_cpu_exit);
+ if (ret < 0) {
+ dev_err(dev, "Failed to setup cpu hotplug state: %i\n", ret);
+ goto free_synic_pages;
+ }
+
+ synic_cpuhp_online = ret;
+
+ ret = register_reboot_notifier(&mshv_synic_reboot_nb);
+ if (ret)
+ goto remove_cpuhp_state;
+
+ return 0;
+
+remove_cpuhp_state:
+ cpuhp_remove_state(synic_cpuhp_online);
+free_synic_pages:
+ free_percpu(synic_pages);
+ return ret;
+}
+
+void mshv_synic_cleanup(void)
+{
+ unregister_reboot_notifier(&mshv_synic_reboot_nb);
+ cpuhp_remove_state(synic_cpuhp_online);
+ free_percpu(synic_pages);
+}
--
2.34.1
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