Re: [PATCH 2/2] KVM: x86: fix KVM_SET_XCRS loop
Il 18/10/2013 02:04, Marcelo Tosatti ha scritto:
> On Thu, Oct 17, 2013 at 04:50:47PM +0200, Paolo Bonzini wrote:
>> The loop was always using 0 as the index. This means that
>> any rubbish after the first element of the array went undetected.
>> It seems reasonable to assume that no KVM userspace did that.
>
> It is not a typo, look at __kvm_set_xcr when setting
> guest_xcrs->xcrs[i].value, with i != 0.
i is not the index of the XCR register, it's the index in the array.
The index is currently hardcoded to 0 when it is passed to
__kvm_set_xcr; but very reasonably __kvm_set_xcr returns 1 when index != 0.
IMO even the "if" in kvm_vcpu_ioctl_x86_set_xcrs is wrong: setting XCR
above XCR0 should fail KVM_SET_XCRS, while currently is ignored. The
body of the loop should be simply:
r = __kvm_set_xcr(vcpu, guest_xcrs->xcrs[i].xcr,
guest_xcrs->xcrs[i].value);
if (r)
break;
Paolo
> The code is not prepared to deal with XCR != 0 (because its not
> implemented in hw).
>
>> Signed-off-by: Paolo Bonzini
>> ---
>> arch/x86/kvm/x86.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index f4e1391..f91dff2 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -3062,9 +3062,9 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu
>> *vcpu,
>>
>> for (i = 0; i < guest_xcrs->nr_xcrs; i++)
>> /* Only support XCR0 currently */
>> -if (guest_xcrs->xcrs[0].xcr == XCR_XFEATURE_ENABLED_MASK) {
>> +if (guest_xcrs->xcrs[i].xcr == XCR_XFEATURE_ENABLED_MASK) {
>> r = __kvm_set_xcr(vcpu, XCR_XFEATURE_ENABLED_MASK,
>> -guest_xcrs->xcrs[0].value);
>> +guest_xcrs->xcrs[i].value);
>> break;
>> }
>> if (r)
>> --
>> 1.8.3.1
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Re: [PATCH 2/2] KVM: x86: fix KVM_SET_XCRS loop
Il 18/10/2013 02:04, Marcelo Tosatti ha scritto:
On Thu, Oct 17, 2013 at 04:50:47PM +0200, Paolo Bonzini wrote:
The loop was always using 0 as the index. This means that
any rubbish after the first element of the array went undetected.
It seems reasonable to assume that no KVM userspace did that.
It is not a typo, look at __kvm_set_xcr when setting
guest_xcrs-xcrs[i].value, with i != 0.
i is not the index of the XCR register, it's the index in the array.
The index is currently hardcoded to 0 when it is passed to
__kvm_set_xcr; but very reasonably __kvm_set_xcr returns 1 when index != 0.
IMO even the if in kvm_vcpu_ioctl_x86_set_xcrs is wrong: setting XCR
above XCR0 should fail KVM_SET_XCRS, while currently is ignored. The
body of the loop should be simply:
r = __kvm_set_xcr(vcpu, guest_xcrs-xcrs[i].xcr,
guest_xcrs-xcrs[i].value);
if (r)
break;
Paolo
The code is not prepared to deal with XCR != 0 (because its not
implemented in hw).
Signed-off-by: Paolo Bonzini pbonz...@redhat.com
---
arch/x86/kvm/x86.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f4e1391..f91dff2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3062,9 +3062,9 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu
*vcpu,
for (i = 0; i guest_xcrs-nr_xcrs; i++)
/* Only support XCR0 currently */
-if (guest_xcrs-xcrs[0].xcr == XCR_XFEATURE_ENABLED_MASK) {
+if (guest_xcrs-xcrs[i].xcr == XCR_XFEATURE_ENABLED_MASK) {
r = __kvm_set_xcr(vcpu, XCR_XFEATURE_ENABLED_MASK,
-guest_xcrs-xcrs[0].value);
+guest_xcrs-xcrs[i].value);
break;
}
if (r)
--
1.8.3.1
--
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Re: [PATCH 2/2] KVM: x86: fix KVM_SET_XCRS loop
On Thu, Oct 17, 2013 at 04:50:47PM +0200, Paolo Bonzini wrote:
> The loop was always using 0 as the index. This means that
> any rubbish after the first element of the array went undetected.
> It seems reasonable to assume that no KVM userspace did that.
It is not a typo, look at __kvm_set_xcr when setting
guest_xcrs->xcrs[i].value, with i != 0.
The code is not prepared to deal with XCR != 0 (because its not
implemented in hw).
> Signed-off-by: Paolo Bonzini
> ---
> arch/x86/kvm/x86.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index f4e1391..f91dff2 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3062,9 +3062,9 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu
> *vcpu,
>
> for (i = 0; i < guest_xcrs->nr_xcrs; i++)
> /* Only support XCR0 currently */
> - if (guest_xcrs->xcrs[0].xcr == XCR_XFEATURE_ENABLED_MASK) {
> + if (guest_xcrs->xcrs[i].xcr == XCR_XFEATURE_ENABLED_MASK) {
> r = __kvm_set_xcr(vcpu, XCR_XFEATURE_ENABLED_MASK,
> - guest_xcrs->xcrs[0].value);
> + guest_xcrs->xcrs[i].value);
> break;
> }
> if (r)
> --
> 1.8.3.1
--
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[PATCH 2/2] KVM: x86: fix KVM_SET_XCRS loop
The loop was always using 0 as the index. This means that
any rubbish after the first element of the array went undetected.
It seems reasonable to assume that no KVM userspace did that.
Signed-off-by: Paolo Bonzini
---
arch/x86/kvm/x86.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f4e1391..f91dff2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3062,9 +3062,9 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu
*vcpu,
for (i = 0; i < guest_xcrs->nr_xcrs; i++)
/* Only support XCR0 currently */
- if (guest_xcrs->xcrs[0].xcr == XCR_XFEATURE_ENABLED_MASK) {
+ if (guest_xcrs->xcrs[i].xcr == XCR_XFEATURE_ENABLED_MASK) {
r = __kvm_set_xcr(vcpu, XCR_XFEATURE_ENABLED_MASK,
- guest_xcrs->xcrs[0].value);
+ guest_xcrs->xcrs[i].value);
break;
}
if (r)
--
1.8.3.1
--
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Please read the FAQ at http://www.tux.org/lkml/
[PATCH 2/2] KVM: x86: fix KVM_SET_XCRS loop
The loop was always using 0 as the index. This means that
any rubbish after the first element of the array went undetected.
It seems reasonable to assume that no KVM userspace did that.
Signed-off-by: Paolo Bonzini pbonz...@redhat.com
---
arch/x86/kvm/x86.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f4e1391..f91dff2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3062,9 +3062,9 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu
*vcpu,
for (i = 0; i guest_xcrs-nr_xcrs; i++)
/* Only support XCR0 currently */
- if (guest_xcrs-xcrs[0].xcr == XCR_XFEATURE_ENABLED_MASK) {
+ if (guest_xcrs-xcrs[i].xcr == XCR_XFEATURE_ENABLED_MASK) {
r = __kvm_set_xcr(vcpu, XCR_XFEATURE_ENABLED_MASK,
- guest_xcrs-xcrs[0].value);
+ guest_xcrs-xcrs[i].value);
break;
}
if (r)
--
1.8.3.1
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH 2/2] KVM: x86: fix KVM_SET_XCRS loop
On Thu, Oct 17, 2013 at 04:50:47PM +0200, Paolo Bonzini wrote:
The loop was always using 0 as the index. This means that
any rubbish after the first element of the array went undetected.
It seems reasonable to assume that no KVM userspace did that.
It is not a typo, look at __kvm_set_xcr when setting
guest_xcrs-xcrs[i].value, with i != 0.
The code is not prepared to deal with XCR != 0 (because its not
implemented in hw).
Signed-off-by: Paolo Bonzini pbonz...@redhat.com
---
arch/x86/kvm/x86.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f4e1391..f91dff2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3062,9 +3062,9 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu
*vcpu,
for (i = 0; i guest_xcrs-nr_xcrs; i++)
/* Only support XCR0 currently */
- if (guest_xcrs-xcrs[0].xcr == XCR_XFEATURE_ENABLED_MASK) {
+ if (guest_xcrs-xcrs[i].xcr == XCR_XFEATURE_ENABLED_MASK) {
r = __kvm_set_xcr(vcpu, XCR_XFEATURE_ENABLED_MASK,
- guest_xcrs-xcrs[0].value);
+ guest_xcrs-xcrs[i].value);
break;
}
if (r)
--
1.8.3.1
--
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the body of a message to majord...@vger.kernel.org
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