diff mbox series

[v2] KVM: move KVM_CAP_DEVICE_CTRL to the generic check

Message ID 20221229123338.4142-1-wei.w.wang@intel.com
State New
Headers
Series [v2] KVM: move KVM_CAP_DEVICE_CTRL to the generic check |

Commit Message

Wang, Wei W Dec. 29, 2022, 12:33 p.m. UTC 
  KVM_CAP_DEVICE_CTRL allows userspace to check if the kvm_device
framework (e.g. KVM_CREATE_DEVICE) is supported by KVM. Move
KVM_CAP_DEVICE_CTRL to the generic check for the two reasons:
1) it already supports arch agnostic usages (i.e. KVM_DEV_TYPE_VFIO).
For example, userspace VFIO implementation may needs to create
KVM_DEV_TYPE_VFIO on x86, riscv, or arm etc. It is simpler to have it
checked at the generic code than at each arch's code.
2) KVM_CREATE_DEVICE has been added to the generic code.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
 arch/arm64/kvm/arm.c       | 1 -
 arch/powerpc/kvm/powerpc.c | 1 -
 arch/riscv/kvm/vm.c        | 1 -
 arch/s390/kvm/kvm-s390.c   | 1 -
 virt/kvm/kvm_main.c        | 1 +
 5 files changed, 1 insertion(+), 4 deletions(-)

Comments

Sean Christopherson Feb. 1, 2023, 11:30 p.m. UTC | #1 
On Thu, Dec 29, 2022, Wei Wang wrote:
> KVM_CAP_DEVICE_CTRL allows userspace to check if the kvm_device
> framework (e.g. KVM_CREATE_DEVICE) is supported by KVM. Move
> KVM_CAP_DEVICE_CTRL to the generic check for the two reasons:
> 1) it already supports arch agnostic usages (i.e. KVM_DEV_TYPE_VFIO).
> For example, userspace VFIO implementation may needs to create
> KVM_DEV_TYPE_VFIO on x86, riscv, or arm etc. It is simpler to have it
> checked at the generic code than at each arch's code.
> 2) KVM_CREATE_DEVICE has been added to the generic code.

I think it's worth adding a link to the v1 patch, as that thread provides the
context for how KVM ended up unconditionally advertising the feature, e.g. instead
of trying to be more precise.

Link: https://lore.kernel.org/all/20221215115207.14784-1-wei.w.wang@intel.com

> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> ---

Reviewed-by: Sean Christopherson <seanjc@google.com>
Wang, Wei W March 8, 2023, 1:31 p.m. UTC | #2 
On Thursday, February 2, 2023 7:30 AM, Sean Christopherson wrote:
> On Thu, Dec 29, 2022, Wei Wang wrote:
> > KVM_CAP_DEVICE_CTRL allows userspace to check if the kvm_device
> > framework (e.g. KVM_CREATE_DEVICE) is supported by KVM. Move
> > KVM_CAP_DEVICE_CTRL to the generic check for the two reasons:
> > 1) it already supports arch agnostic usages (i.e. KVM_DEV_TYPE_VFIO).
> > For example, userspace VFIO implementation may needs to create
> > KVM_DEV_TYPE_VFIO on x86, riscv, or arm etc. It is simpler to have it
> > checked at the generic code than at each arch's code.
> > 2) KVM_CREATE_DEVICE has been added to the generic code.
> 
> I think it's worth adding a link to the v1 patch, as that thread provides the
> context for how KVM ended up unconditionally advertising the feature, e.g.
> instead of trying to be more precise.
> 
> Link: https://lore.kernel.org/all/20221215115207.14784-1-
> wei.w.wang@intel.com
> 
> > Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> > ---
> 
> Reviewed-by: Sean Christopherson <seanjc@google.com>
Thanks.

Is this patch ready to be merged along with the link or
need me to re-send to have the link added?
diff mbox series

Patch

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 9c5573bc4614..190e9c3b10a7 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -212,7 +212,6 @@  int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		r = vgic_present;
 		break;
 	case KVM_CAP_IOEVENTFD:
-	case KVM_CAP_DEVICE_CTRL:
 	case KVM_CAP_USER_MEMORY:
 	case KVM_CAP_SYNC_MMU:
 	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 04494a4fb37a..21f9fbe96f6a 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -541,7 +541,6 @@  int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_ENABLE_CAP:
 	case KVM_CAP_ONE_REG:
 	case KVM_CAP_IOEVENTFD:
-	case KVM_CAP_DEVICE_CTRL:
 	case KVM_CAP_IMMEDIATE_EXIT:
 	case KVM_CAP_SET_GUEST_DEBUG:
 		r = 1;
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index 65a964d7e70d..6efe93b282e1 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -57,7 +57,6 @@  int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 
 	switch (ext) {
 	case KVM_CAP_IOEVENTFD:
-	case KVM_CAP_DEVICE_CTRL:
 	case KVM_CAP_USER_MEMORY:
 	case KVM_CAP_SYNC_MMU:
 	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index e4890e04b210..191d220b6a30 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -567,7 +567,6 @@  int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_ENABLE_CAP:
 	case KVM_CAP_S390_CSS_SUPPORT:
 	case KVM_CAP_IOEVENTFD:
-	case KVM_CAP_DEVICE_CTRL:
 	case KVM_CAP_S390_IRQCHIP:
 	case KVM_CAP_VM_ATTRIBUTES:
 	case KVM_CAP_MP_STATE:
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 582757ebdce6..84073464aea0 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4524,6 +4524,7 @@  static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
 #endif
 	case KVM_CAP_BINARY_STATS_FD:
 	case KVM_CAP_SYSTEM_EVENT_DATA:
+	case KVM_CAP_DEVICE_CTRL:
 		return 1;
 	default:
 		break;