[Qemu-devel] [PATCH v3 0/2] actual checks of KVM_CAP_IRQFD and KVM_CAP_IRQFD_RESAMPLE

[Qemu-devel] [PATCH v3 0/2] actual checks of KVM_CAP_IRQFD and KVM_CAP_IRQFD_RESAMPLE

[Eric Auger]

This patch series replaces direct settings of kvm_irqfds_allowed
in architecture specific files by actual check of the KVM_CAP_IRQFD
extension in kvm-all.c.

Also A new kvm_resamplefds_enabled() enables to check
KVM_CAP_IRQFD_RESAMPLE. In the second patch file the vfio device
becomes the first user of kvm_resamplefds_enabled().

Eric Auger (2):
  KVM_CAP_IRQFD and KVM_CAP_IRQFD_RESAMPLE checks
  vfio: use kvm_resamplefds_enabled()

 hw/intc/openpic_kvm.c |  1 -
 hw/intc/xics_kvm.c    |  1 -
 hw/misc/vfio.c        |  5 ++---
 include/sysemu/kvm.h  | 10 ++++++++++
 kvm-all.c             |  7 +++++++
 target-i386/kvm.c     |  1 -
 target-s390x/kvm.c    |  1 -
 7 files changed, 19 insertions(+), 7 deletions(-)

-- 
1.8.3.2

[Qemu-devel] [PATCH v3 1/2] KVM_CAP_IRQFD and KVM_CAP_IRQFD_RESAMPLE checks

[Eric Auger]

Compute kvm_irqfds_allowed by checking the KVM_CAP_IRQFD extension.
Remove direct settings in architecture specific files.

Add a new kvm_resamplefds_allowed variable, initialized by
checking the KVM_CAP_IRQFD_RESAMPLE extension. Add a corresponding
kvm_resamplefds_enabled() function.

A special notice for s390 where KVM_CAP_IRQFD was not immediatly
advirtised when irqfd capability was introduced in the kernel.
KVM_CAP_IRQ_ROUTING was advertised instead.

This was fixed in "KVM: s390: announce irqfd capability",
ebc3226202d5956a5963185222982d435378b899 whereas irqfd support
was brought in 84223598778ba08041f4297fda485df83414d57e,
"KVM: s390: irq routing for adapter interrupts".  Both commits
first appear in 3.15 so there should not be any kernel
version impacted by this QEMU modification.

Signed-off-by: Eric Auger <eric.auger@linaro.org>

---

v2->v3:
- changed the commit message only
---
 hw/intc/openpic_kvm.c |  1 -
 hw/intc/xics_kvm.c    |  1 -
 include/sysemu/kvm.h  | 10 ++++++++++
 kvm-all.c             |  7 +++++++
 target-i386/kvm.c     |  1 -
 target-s390x/kvm.c    |  1 -
 6 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/hw/intc/openpic_kvm.c b/hw/intc/openpic_kvm.c
index e3bce04..6cef3b1 100644
--- a/hw/intc/openpic_kvm.c
+++ b/hw/intc/openpic_kvm.c
@@ -229,7 +229,6 @@ static void kvm_openpic_realize(DeviceState *dev, Error **errp)
         kvm_irqchip_add_irq_route(kvm_state, i, 0, i);
     }
 
-    kvm_irqfds_allowed = true;
     kvm_msi_via_irqfd_allowed = true;
     kvm_gsi_routing_allowed = true;
 
diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index 20b19e9..c15453f 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -448,7 +448,6 @@ static void xics_kvm_realize(DeviceState *dev, Error **errp)
     }
 
     kvm_kernel_irqchip = true;
-    kvm_irqfds_allowed = true;
     kvm_msi_via_irqfd_allowed = true;
     kvm_gsi_direct_mapping = true;
 
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index b0cd657..a23ddab 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -45,6 +45,7 @@ extern bool kvm_async_interrupts_allowed;
 extern bool kvm_halt_in_kernel_allowed;
 extern bool kvm_eventfds_allowed;
 extern bool kvm_irqfds_allowed;
+extern bool kvm_resamplefds_allowed;
 extern bool kvm_msi_via_irqfd_allowed;
 extern bool kvm_gsi_routing_allowed;
 extern bool kvm_gsi_direct_mapping;
@@ -102,6 +103,15 @@ extern bool kvm_readonly_mem_allowed;
 #define kvm_irqfds_enabled() (kvm_irqfds_allowed)
 
 /**
+ * kvm_resamplefds_enabled:
+ *
+ * Returns: true if we can use resamplefds to inject interrupts into
+ * a KVM CPU (ie the kernel supports resamplefds and we are running
+ * with a configuration where it is meaningful to use them).
+ */
+#define kvm_resamplefds_enabled() (kvm_resamplefds_allowed)
+
+/**
  * kvm_msi_via_irqfd_enabled:
  *
  * Returns: true if we can route a PCI MSI (Message Signaled Interrupt)
diff --git a/kvm-all.c b/kvm-all.c
index 44a5e72..0a3139f 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -120,6 +120,7 @@ bool kvm_async_interrupts_allowed;
 bool kvm_halt_in_kernel_allowed;
 bool kvm_eventfds_allowed;
 bool kvm_irqfds_allowed;
+bool kvm_resamplefds_allowed;
 bool kvm_msi_via_irqfd_allowed;
 bool kvm_gsi_routing_allowed;
 bool kvm_gsi_direct_mapping;
@@ -1566,6 +1567,12 @@ static int kvm_init(MachineState *ms)
     kvm_eventfds_allowed =
         (kvm_check_extension(s, KVM_CAP_IOEVENTFD) > 0);
 
+    kvm_irqfds_allowed =
+        (kvm_check_extension(s, KVM_CAP_IRQFD) > 0);
+
+    kvm_resamplefds_allowed =
+        (kvm_check_extension(s, KVM_CAP_IRQFD_RESAMPLE) > 0);
+
     ret = kvm_arch_init(s);
     if (ret < 0) {
         goto err;
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index ccf36e8..3a3dfc4 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -2563,7 +2563,6 @@ void kvm_arch_init_irq_routing(KVMState *s)
      * irqchip, so we can use irqfds, and on x86 we know
      * we can use msi via irqfd and GSI routing.
      */
-    kvm_irqfds_allowed = true;
     kvm_msi_via_irqfd_allowed = true;
     kvm_gsi_routing_allowed = true;
 }
diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
index 5b10a25..9ae1958 100644
--- a/target-s390x/kvm.c
+++ b/target-s390x/kvm.c
@@ -1294,7 +1294,6 @@ void kvm_arch_init_irq_routing(KVMState *s)
      * have to override the common code kvm_halt_in_kernel_allowed setting.
      */
     if (kvm_check_extension(s, KVM_CAP_IRQ_ROUTING)) {
-        kvm_irqfds_allowed = true;
         kvm_gsi_routing_allowed = true;
         kvm_halt_in_kernel_allowed = false;
     }
-- 
1.8.3.2

Re: [Qemu-devel] [PATCH v3 1/2] KVM_CAP_IRQFD and KVM_CAP_IRQFD_RESAMPLE checks

[Cornelia Huck]

On Fri, 31 Oct 2014 13:38:18 +0000
Eric Auger <eric.auger@linaro.org> wrote:

> Compute kvm_irqfds_allowed by checking the KVM_CAP_IRQFD extension.
> Remove direct settings in architecture specific files.
> 
> Add a new kvm_resamplefds_allowed variable, initialized by
> checking the KVM_CAP_IRQFD_RESAMPLE extension. Add a corresponding
> kvm_resamplefds_enabled() function.
> 
> A special notice for s390 where KVM_CAP_IRQFD was not immediatly
> advirtised when irqfd capability was introduced in the kernel.

s/immediatly advirtised/immediately advertised/

> KVM_CAP_IRQ_ROUTING was advertised instead.
> 
> This was fixed in "KVM: s390: announce irqfd capability",
> ebc3226202d5956a5963185222982d435378b899 whereas irqfd support
> was brought in 84223598778ba08041f4297fda485df83414d57e,
> "KVM: s390: irq routing for adapter interrupts".  Both commits
> first appear in 3.15 so there should not be any kernel
> version impacted by this QEMU modification.

Yes, I think we can live with disabling irqfd support for those
versions inbetween :)

> 
> Signed-off-by: Eric Auger <eric.auger@linaro.org>

The patch looks sane to me and I verified that qemu works as expected
on s390 (current kernel, current kernel with KVM_CAP_IRQFD disabled
again and pre-KVM_CAP_IRQ_ROUTING). So:

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Tested-by: Cornelia Huck <cornelia.huck@de.ibm.com>

[Qemu-devel] [PATCH v3 2/2] vfio: use kvm_resamplefds_enabled()

[Eric Auger]

Use the kvm_resamplefds_enabled function

Signed-off-by: Eric Auger <eric.auger@linaro.org>
---
 hw/misc/vfio.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index b5e7981..75bfa1c 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -406,7 +406,7 @@ static void vfio_enable_intx_kvm(VFIODevice *vdev)
 
     if (!VFIO_ALLOW_KVM_INTX || !kvm_irqfds_enabled() ||
         vdev->intx.route.mode != PCI_INTX_ENABLED ||
-        !kvm_check_extension(kvm_state, KVM_CAP_IRQFD_RESAMPLE)) {
+        !kvm_resamplefds_enabled()) {
         return;
     }
 
@@ -568,8 +568,7 @@ static int vfio_enable_intx(VFIODevice *vdev)
      * Only conditional to avoid generating error messages on platforms
      * where we won't actually use the result anyway.
      */
-    if (kvm_irqfds_enabled() &&
-        kvm_check_extension(kvm_state, KVM_CAP_IRQFD_RESAMPLE)) {
+    if (kvm_irqfds_enabled() && kvm_resamplefds_enabled()) {
         vdev->intx.route = pci_device_route_intx_to_irq(&vdev->pdev,
                                                         vdev->intx.pin);
     }
-- 
1.8.3.2

Re: [Qemu-devel] [PATCH v3 2/2] vfio: use kvm_resamplefds_enabled()

[Alex Williamson]

On Fri, 2014-10-31 at 13:38 +0000, Eric Auger wrote:
> Use the kvm_resamplefds_enabled function
> 
> Signed-off-by: Eric Auger <eric.auger@linaro.org>
> ---

If someone wants to pick this up:

Acked-by: Alex Williamson <alex.williamson@redhat.com>

Alternatively, provide an ack on patch 1 and I can bring it in through
my tree after 2.2.  Thanks,

Alex

>  hw/misc/vfio.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
> index b5e7981..75bfa1c 100644
> --- a/hw/misc/vfio.c
> +++ b/hw/misc/vfio.c
> @@ -406,7 +406,7 @@ static void vfio_enable_intx_kvm(VFIODevice *vdev)
>  
>      if (!VFIO_ALLOW_KVM_INTX || !kvm_irqfds_enabled() ||
>          vdev->intx.route.mode != PCI_INTX_ENABLED ||
> -        !kvm_check_extension(kvm_state, KVM_CAP_IRQFD_RESAMPLE)) {
> +        !kvm_resamplefds_enabled()) {
>          return;
>      }
>  
> @@ -568,8 +568,7 @@ static int vfio_enable_intx(VFIODevice *vdev)
>       * Only conditional to avoid generating error messages on platforms
>       * where we won't actually use the result anyway.
>       */
> -    if (kvm_irqfds_enabled() &&
> -        kvm_check_extension(kvm_state, KVM_CAP_IRQFD_RESAMPLE)) {
> +    if (kvm_irqfds_enabled() && kvm_resamplefds_enabled()) {
>          vdev->intx.route = pci_device_route_intx_to_irq(&vdev->pdev,
>                                                          vdev->intx.pin);
>      }

Re: [Qemu-devel] [PATCH v3 2/2] vfio: use kvm_resamplefds_enabled()

[Paolo Bonzini]

On 04/11/2014 23:25, Alex Williamson wrote:
> Acked-by: Alex Williamson <alex.williamson@redhat.com>

Thanks, I'll get it into the KVM tree (uq/master).

Paolo

Re: [Qemu-devel] [PATCH v3 0/2] actual checks of KVM_CAP_IRQFD and KVM_CAP_IRQFD_RESAMPLE

[Paolo Bonzini]

On 31/10/2014 14:38, Eric Auger wrote:
> This patch series replaces direct settings of kvm_irqfds_allowed
> in architecture specific files by actual check of the KVM_CAP_IRQFD
> extension in kvm-all.c.
> 
> Also A new kvm_resamplefds_enabled() enables to check
> KVM_CAP_IRQFD_RESAMPLE. In the second patch file the vfio device
> becomes the first user of kvm_resamplefds_enabled().
> 
> Eric Auger (2):
>   KVM_CAP_IRQFD and KVM_CAP_IRQFD_RESAMPLE checks
>   vfio: use kvm_resamplefds_enabled()
> 
>  hw/intc/openpic_kvm.c |  1 -
>  hw/intc/xics_kvm.c    |  1 -
>  hw/misc/vfio.c        |  5 ++---
>  include/sysemu/kvm.h  | 10 ++++++++++
>  kvm-all.c             |  7 +++++++
>  target-i386/kvm.c     |  1 -
>  target-s390x/kvm.c    |  1 -
>  7 files changed, 19 insertions(+), 7 deletions(-)
> 

Applied for 2.3 to uq/master.  Thanks.

Paolo