* [PATCH] KVM: x86: do not save guest-unsupported XSAVE state
@ 2017-02-01 13:19 Radim Krčmář
2017-02-02 0:13 ` Paolo Bonzini
0 siblings, 1 reply; 3+ messages in thread
From: Radim Krčmář @ 2017-02-01 13:19 UTC (permalink / raw)
To: linux-kernel, kvm; +Cc: Paolo Bonzini
Saving unsupported state prevents migration when the new host does not
support a XSAVE feature of the original host, even if the feature is not
exposed to the guest.
We've masked host features with guest-visible features before, with
4344ee981e21 ("KVM: x86: only copy XSAVE state for the supported
features") and dropped it when implementing XSAVES. Do it again.
Fixes: df1daba7d1cb ("KVM: x86: support XSAVES usage in the host")
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
arch/x86/kvm/x86.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 96dd7dd13ee6..5f013ad89b57 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3221,6 +3221,7 @@ static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
memcpy(dest, xsave, XSAVE_HDR_OFFSET);
/* Set XSTATE_BV */
+ xstate_bv &= vcpu->arch.guest_supported_xcr0 | XFEATURE_MASK_FPSSE;
*(u64 *)(dest + XSAVE_HDR_OFFSET) = xstate_bv;
/*
--
2.11.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: x86: do not save guest-unsupported XSAVE state
2017-02-01 13:19 [PATCH] KVM: x86: do not save guest-unsupported XSAVE state Radim Krčmář
@ 2017-02-02 0:13 ` Paolo Bonzini
2017-02-04 16:26 ` Radim Krčmář
0 siblings, 1 reply; 3+ messages in thread
From: Paolo Bonzini @ 2017-02-02 0:13 UTC (permalink / raw)
To: Radim Krčmář, linux-kernel, kvm, stable
On 01/02/2017 05:19, Radim Krčmář wrote:
> Saving unsupported state prevents migration when the new host does not
> support a XSAVE feature of the original host, even if the feature is not
> exposed to the guest.
>
> We've masked host features with guest-visible features before, with
> 4344ee981e21 ("KVM: x86: only copy XSAVE state for the supported
> features") and dropped it when implementing XSAVES. Do it again.
>
> Fixes: df1daba7d1cb ("KVM: x86: support XSAVES usage in the host")
> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Please apply to kvm/master and send it yourself to Linus since I don't
have access to my machine this week.
Paolo
> ---
> arch/x86/kvm/x86.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 96dd7dd13ee6..5f013ad89b57 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3221,6 +3221,7 @@ static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
> memcpy(dest, xsave, XSAVE_HDR_OFFSET);
>
> /* Set XSTATE_BV */
> + xstate_bv &= vcpu->arch.guest_supported_xcr0 | XFEATURE_MASK_FPSSE;
> *(u64 *)(dest + XSAVE_HDR_OFFSET) = xstate_bv;
>
> /*
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: x86: do not save guest-unsupported XSAVE state
2017-02-02 0:13 ` Paolo Bonzini
@ 2017-02-04 16:26 ` Radim Krčmář
0 siblings, 0 replies; 3+ messages in thread
From: Radim Krčmář @ 2017-02-04 16:26 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: linux-kernel, kvm, stable
2017-02-01 16:13-0800, Paolo Bonzini:
> On 01/02/2017 05:19, Radim Krčmář wrote:
>> Saving unsupported state prevents migration when the new host does not
>> support a XSAVE feature of the original host, even if the feature is not
>> exposed to the guest.
>>
>> We've masked host features with guest-visible features before, with
>> 4344ee981e21 ("KVM: x86: only copy XSAVE state for the supported
>> features") and dropped it when implementing XSAVES. Do it again.
>>
>> Fixes: df1daba7d1cb ("KVM: x86: support XSAVES usage in the host")
>> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
>
> Cc: stable@vger.kernel.org
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
>
> Please apply to kvm/master and send it yourself to Linus since I don't
> have access to my machine this week.
Done, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-02-04 16:26 UTC | newest]
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2017-02-01 13:19 [PATCH] KVM: x86: do not save guest-unsupported XSAVE state Radim Krčmář
2017-02-02 0:13 ` Paolo Bonzini
2017-02-04 16:26 ` Radim Krčmář
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