[PATCH v5 09/22] KVM: arm64: vgic-its: Introduce migration ABI infrastructure

Eric Auger
2017-04-14T10:16:47Z

We plan to support different migration ABIs, ie. characterizing
the ITS table layout format in guest RAM. Typically a new ABI will
be needed if vLPIs get supported for nested use case.

So let's introduce an array of supported ABIs (at the moment a single
ABI is supported though). The following characteristics are foreseen
to vary with the ABI: size of table entries, save/restore operation.

By default the MAX_ABI_REV is applied on its creation. In subsequent
patches we will introduce a way for the userspace to change the ABI
in use.

The entry sizes now are set according to the ABI version and not
hardcoded anymore.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

v5: creation and squash KVM: arm64: ITS: Report the ITE size in
GITS_TYPER
---
include/kvm/arm_vgic.h | 3 ++
include/linux/irqchip/arm-gic-v3.h | 4 ++
virt/kvm/arm/vgic/vgic-its.c | 82 ++++++++++++++++++++++++++++++++++++--
3 files changed, 85 insertions(+), 4 deletions(-)

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index c0b3d99..285474a 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -162,6 +162,9 @@ struct vgic_its {
u32 creadr;
u32 cwriter;

+ /* migration ABI revision in use */
+ u32 abi_rev;
+
/* Protects the device and collection lists */
struct mutex its_lock;
struct list_head device_list;
diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index 97cbca1..9648bad 100644
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -132,6 +132,8 @@
#define GIC_BASER_SHAREABILITY(reg, type) \
(GIC_BASER_##type << reg##_SHAREABILITY_SHIFT)

+#define GIC_ENCODE_SZ(n, w) (((unsigned long)(n) - 1) & GENMASK_ULL(((w) - 1), 0))
+
#define GICR_PROPBASER_SHAREABILITY_SHIFT (10)
#define GICR_PROPBASER_INNER_CACHEABILITY_SHIFT (7)
#define GICR_PROPBASER_OUTER_CACHEABILITY_SHIFT (56)
@@ -232,6 +234,7 @@
#define GITS_CTLR_QUIESCENT (1U << 31)

#define GITS_TYPER_PLPIS (1UL << 0)
+#define GITS_TYPER_ITT_ENTRY_SIZE_SHIFT 4
#define GITS_TYPER_IDBITS_SHIFT 8
#define GITS_TYPER_DEVBITS_SHIFT 13
#define GITS_TYPER_DEVBITS(r) ((((r) >> GITS_TYPER_DEVBITS_SHIFT) & 0x1f) + 1)
@@ -290,6 +293,7 @@
#define GITS_BASER_TYPE(r) (((r) >> GITS_BASER_TYPE_SHIFT) & 7)
#define GITS_BASER_ENTRY_SIZE_SHIFT (48)
#define GITS_BASER_ENTRY_SIZE(r) ((((r) >> GITS_BASER_ENTRY_SIZE_SHIFT) & 0x1f) + 1)
+#define GITS_BASER_ENTRY_SIZE_MASK GENMASK_ULL(52, 48)
#define GITS_BASER_SHAREABILITY_SHIFT (10)
#define GITS_BASER_InnerShareable \
GIC_BASER_SHAREABILITY(GITS_BASER, InnerShareable)
diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 79ed1c2..69ecfe4 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -33,6 +33,12 @@
#include "vgic.h"
#include "vgic-mmio.h"

+/* Highest migration ABI revision supported by this code */
+#define MAX_ABI_REV 0
+
+static int vgic_its_set_abi(struct vgic_its *its, int rev);
+static const struct vgic_its_abi *vgic_its_get_abi(struct vgic_its *its);
+
/*
* Creates a new (reference to a) struct vgic_irq for a given LPI.
* If this LPI is already mapped on another ITS, we increase its refcount
@@ -123,6 +129,15 @@ struct its_ite {
u32 event_id;
};

+struct vgic_its_abi {
+ int cte_esz;
+ int dte_esz;
+ int ite_esz;
+ int (*save_tables)(struct vgic_its *its);
+ int (*restore_tables)(struct vgic_its *its);
+ int (*commit)(struct vgic_its *its);
+};
+
/*
* Find and returns a device in the device table for an ITS.
* Must be called with the its_lock mutex held.
@@ -364,6 +379,7 @@ static unsigned long vgic_mmio_read_its_typer(struct kvm *kvm,
struct vgic_its *its,
gpa_t addr, unsigned int len)
{
+ const struct vgic_its_abi *abi = vgic_its_get_abi(its);
u64 reg = GITS_TYPER_PLPIS;

/*
@@ -376,6 +392,7 @@ static unsigned long vgic_mmio_read_its_typer(struct kvm *kvm,
*/
reg |= 0x0f << GITS_TYPER_DEVBITS_SHIFT;
reg |= 0x0f << GITS_TYPER_IDBITS_SHIFT;
+ reg |= GIC_ENCODE_SZ(abi->ite_esz, 4) << GITS_TYPER_ITT_ENTRY_SIZE_SHIFT;

return extract_bytes(reg, addr & 7, len);
}
@@ -1268,6 +1285,7 @@ static void vgic_mmio_write_its_baser(struct kvm *kvm,
gpa_t addr, unsigned int len,
unsigned long val)
{
+ const struct vgic_its_abi *abi = vgic_its_get_abi(its);
u64 entry_size, device_type;
u64 reg, *regptr, clearbits = 0;

@@ -1278,12 +1296,12 @@ static void vgic_mmio_write_its_baser(struct kvm *kvm,
switch (BASER_INDEX(addr)) {
case 0:
regptr = &its->baser_device_table;
- entry_size = 8;
+ entry_size = abi->dte_esz;
device_type = GITS_BASER_TYPE_DEVICE;
break;
case 1:
regptr = &its->baser_coll_table;
- entry_size = 8;
+ entry_size = abi->cte_esz;
device_type = GITS_BASER_TYPE_COLLECTION;
clearbits = GITS_BASER_INDIRECT;
break;
@@ -1425,7 +1443,6 @@ static int vgic_register_its_iodev(struct kvm *kvm, struct vgic_its *its)
(GIC_BASER_CACHEABILITY(GITS_BASER, INNER, RaWb) | \
GIC_BASER_CACHEABILITY(GITS_BASER, OUTER, SameAsInner) | \
GIC_BASER_SHAREABILITY(GITS_BASER, InnerShareable) | \
- ((8ULL - 1) << GITS_BASER_ENTRY_SIZE_SHIFT) | \
GITS_BASER_PAGE_SIZE_64K)

#define INITIAL_PROPBASER_VALUE \
@@ -1465,7 +1482,7 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)

dev->private = its;

- return 0;
+ return vgic_its_set_abi(its, MAX_ABI_REV);
}

static void vgic_its_destroy(struct kvm_device *kvm_dev)
@@ -1592,6 +1609,63 @@ int vgic_its_attr_regs_access(struct kvm_device *dev,
return ret;
}

+/**
+ * vgic_its_save_tables_v0 - Save the ITS tables into guest ARM
+ * according to v0 ABI
+ */
+static int vgic_its_save_tables_v0(struct vgic_its *its)
+{
+ return -ENXIO;
+}
+
+/**
+ * vgic_its_restore_tables_v0 - Restore the ITS tables from guest RAM
+ * to internal data structs according to V0 ABI
+ *
+ */
+static int vgic_its_restore_tables_v0(struct vgic_its *its)
+{
+ return -ENXIO;
+}
+
+static int vgic_its_commit_v0(struct vgic_its *its)
+{
+ const struct vgic_its_abi *abi;
+
+ abi = vgic_its_get_abi(its);
+ its->baser_coll_table &= ~GITS_BASER_ENTRY_SIZE_MASK;
+ its->baser_device_table &= ~GITS_BASER_ENTRY_SIZE_MASK;
+
+ its->baser_coll_table |= (GIC_ENCODE_SZ(abi->cte_esz, 5)
+ << GITS_BASER_ENTRY_SIZE_SHIFT);
+
+ its->baser_device_table |= (GIC_ENCODE_SZ(abi->dte_esz, 5)
+ << GITS_BASER_ENTRY_SIZE_SHIFT);
+ return 0;
+}
+
+static const struct vgic_its_abi abi[MAX_ABI_REV + 1] = {
+ {.cte_esz = 8, .dte_esz = 8, .ite_esz = 8,
+ .save_tables = vgic_its_save_tables_v0,
+ .restore_tables = vgic_its_restore_tables_v0,
+ . commit = vgic_its_commit_v0,
+ },
+};
+
+inline const struct vgic_its_abi *vgic_its_get_abi(struct vgic_its *its)
+{
+ return &abi[its->abi_rev];
+}
+
+int vgic_its_set_abi(struct vgic_its *its, int rev)
+{
+ const struct vgic_its_abi *abi;
+
+ its->abi_rev = rev;
+ abi = vgic_its_get_abi(its);
+ return abi->commit(its);
+}
+
static int vgic_its_has_attr(struct kvm_device *dev,
struct kvm_device_attr *attr)
{
--
2.5.5