From: Sean Christopherson <[email protected]>
Since VMX and SVM both would never update the control bits if exits
are disable after vCPUs are created, only allow setting exits
disable flag before vCPU creation.
Fixes: 4d5422cea3b6 ("KVM: X86: Provide a capability to disable MWAIT
intercepts")
Signed-off-by: Sean Christopherson <[email protected]>
Signed-off-by: Kechen Lu <[email protected]>
---
Documentation/virt/kvm/api.rst | 1 +
arch/x86/kvm/x86.c | 6 ++++++
2 files changed, 7 insertions(+)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 11e00a46c610..d0d8749591a8 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -6933,6 +6933,7 @@ branch to guests' 0x200 interrupt vector.
:Architectures: x86
:Parameters: args[0] defines which exits are disabled
:Returns: 0 on success, -EINVAL when args[0] contains invalid exits
+ or if any vCPU has already been created
Valid bits in args[0] are::
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 158b2e135efc..3ac6329e6d43 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6006,6 +6006,10 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
if (cap->args[0] & ~KVM_X86_DISABLE_VALID_EXITS)
break;
+ mutex_lock(&kvm->lock);
+ if (kvm->created_vcpus)
+ goto disable_exits_unlock;
+
if ((cap->args[0] & KVM_X86_DISABLE_EXITS_MWAIT) &&
kvm_can_mwait_in_guest())
kvm->arch.mwait_in_guest = true;
@@ -6016,6 +6020,8 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
if (cap->args[0] & KVM_X86_DISABLE_EXITS_CSTATE)
kvm->arch.cstate_in_guest = true;
r = 0;
+disable_exits_unlock:
+ mutex_unlock(&kvm->lock);
break;
case KVM_CAP_MSR_PLATFORM_INFO:
kvm->arch.guest_can_read_msr_platform_info = cap->args[0];
--
2.32.0
On Wed, Jul 20, 2022, Sean Christopherson wrote:
> On Tue, Jun 14, 2022, Kechen Lu wrote:
> > From: Sean Christopherson <[email protected]>
> >
> > Since VMX and SVM both would never update the control bits if exits
> > are disable after vCPUs are created, only allow setting exits
> > disable flag before vCPU creation.
> >
> > Fixes: 4d5422cea3b6 ("KVM: X86: Provide a capability to disable MWAIT
> > intercepts")
>
> Don't wrap the Fixes: line (ignore any complaints from checkpatch).
Sorry, I didn't see that you had sent v4 already and replied to some v3 patches.
This one still holds true for v4 (very minor nit though).
On Tue, Jun 14, 2022, Kechen Lu wrote:
> From: Sean Christopherson <[email protected]>
>
> Since VMX and SVM both would never update the control bits if exits
> are disable after vCPUs are created, only allow setting exits
> disable flag before vCPU creation.
>
> Fixes: 4d5422cea3b6 ("KVM: X86: Provide a capability to disable MWAIT
> intercepts")
Don't wrap the Fixes: line (ignore any complaints from checkpatch).
> Signed-off-by: Sean Christopherson <[email protected]>
> Signed-off-by: Kechen Lu <[email protected]>
> ---
> -----Original Message-----
> From: Sean Christopherson <[email protected]>
> Sent: Wednesday, July 20, 2022 10:50 AM
> To: Kechen Lu <[email protected]>
> Cc: [email protected]; [email protected]; [email protected];
> Somdutta Roy <[email protected]>; [email protected]
> Subject: Re: [RFC PATCH v3 1/7] KVM: x86: only allow exits disable before
> vCPUs created
>
> External email: Use caution opening links or attachments
>
>
> On Wed, Jul 20, 2022, Sean Christopherson wrote:
> > On Tue, Jun 14, 2022, Kechen Lu wrote:
> > > From: Sean Christopherson <[email protected]>
> > >
> > > Since VMX and SVM both would never update the control bits if exits
> > > are disable after vCPUs are created, only allow setting exits
> > > disable flag before vCPU creation.
> > >
> > > Fixes: 4d5422cea3b6 ("KVM: X86: Provide a capability to disable
> > > MWAIT
> > > intercepts")
> >
> > Don't wrap the Fixes: line (ignore any complaints from checkpatch).
>
> Sorry, I didn't see that you had sent v4 already and replied to some v3
> patches.
> This one still holds true for v4 (very minor nit though).
Sure:)