* [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset
@ 2022-01-17 8:26 Like Xu
2022-01-17 17:32 ` Paolo Bonzini
2022-01-18 18:30 ` [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset Sean Christopherson
0 siblings, 2 replies; 9+ messages in thread
From: Like Xu @ 2022-01-17 8:26 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Wanpeng Li, Sean Christopherson, Jim Mattson, Vitaly Kuznetsov,
Joerg Roedel, kvm, linux-kernel
From: Like Xu <likexu@tencent.com>
XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by
both RESET and INIT. In both cases, the size in bytes of the XSAVE
area containing all states enabled by XCR0 or (XCRO | IA32_XSS)
needs to be updated.
Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
Signed-off-by: Like Xu <likexu@tencent.com>
---
arch/x86/kvm/x86.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 76b4803dd3bd..5748a57e1cb7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11134,6 +11134,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
struct kvm_cpuid_entry2 *cpuid_0x1;
unsigned long old_cr0 = kvm_read_cr0(vcpu);
unsigned long new_cr0;
+ bool need_update_cpuid = false;
/*
* Several of the "set" flows, e.g. ->set_cr0(), read other registers
@@ -11199,6 +11200,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
vcpu->arch.msr_misc_features_enables = 0;
+ if (vcpu->arch.xcr0 != XFEATURE_MASK_FP)
+ need_update_cpuid = true;
vcpu->arch.xcr0 = XFEATURE_MASK_FP;
}
@@ -11216,6 +11219,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
+ if (vcpu->arch.ia32_xss)
+ need_update_cpuid = true;
vcpu->arch.ia32_xss = 0;
static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
@@ -11264,6 +11269,9 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
*/
if (init_event)
kvm_make_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu);
+
+ if (need_update_cpuid)
+ kvm_update_cpuid_runtime(vcpu);
}
EXPORT_SYMBOL_GPL(kvm_vcpu_reset);
--
2.33.1
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset
2022-01-17 8:26 [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset Like Xu
@ 2022-01-17 17:32 ` Paolo Bonzini
2022-01-21 4:09 ` [PATCH v2] KVM: x86: Sync the states size with the XCR0/IA32_XSS at any time Like Xu
2022-01-18 18:30 ` [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset Sean Christopherson
1 sibling, 1 reply; 9+ messages in thread
From: Paolo Bonzini @ 2022-01-17 17:32 UTC (permalink / raw)
To: Like Xu
Cc: Wanpeng Li, Sean Christopherson, Jim Mattson, Vitaly Kuznetsov,
Joerg Roedel, kvm, linux-kernel
On 1/17/22 09:26, Like Xu wrote:
> From: Like Xu <likexu@tencent.com>
>
> XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by
> both RESET and INIT. In both cases, the size in bytes of the XSAVE
> area containing all states enabled by XCR0 or (XCRO | IA32_XSS)
> needs to be updated.
>
> Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
> Signed-off-by: Like Xu <likexu@tencent.com>
Can you write a test case please?
Thanks,
Paolo
> ---
> arch/x86/kvm/x86.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 76b4803dd3bd..5748a57e1cb7 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -11134,6 +11134,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> struct kvm_cpuid_entry2 *cpuid_0x1;
> unsigned long old_cr0 = kvm_read_cr0(vcpu);
> unsigned long new_cr0;
> + bool need_update_cpuid = false;
>
> /*
> * Several of the "set" flows, e.g. ->set_cr0(), read other registers
> @@ -11199,6 +11200,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>
> vcpu->arch.msr_misc_features_enables = 0;
>
> + if (vcpu->arch.xcr0 != XFEATURE_MASK_FP)
> + need_update_cpuid = true;
> vcpu->arch.xcr0 = XFEATURE_MASK_FP;
> }
>
> @@ -11216,6 +11219,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
> kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
>
> + if (vcpu->arch.ia32_xss)
> + need_update_cpuid = true;
> vcpu->arch.ia32_xss = 0;
>
> static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
> @@ -11264,6 +11269,9 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> */
> if (init_event)
> kvm_make_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu);
> +
> + if (need_update_cpuid)
> + kvm_update_cpuid_runtime(vcpu);
> }
> EXPORT_SYMBOL_GPL(kvm_vcpu_reset);
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset
2022-01-17 8:26 [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset Like Xu
2022-01-17 17:32 ` Paolo Bonzini
@ 2022-01-18 18:30 ` Sean Christopherson
2022-01-19 7:25 ` Like Xu
1 sibling, 1 reply; 9+ messages in thread
From: Sean Christopherson @ 2022-01-18 18:30 UTC (permalink / raw)
To: Like Xu
Cc: Paolo Bonzini, Wanpeng Li, Jim Mattson, Vitaly Kuznetsov,
Joerg Roedel, kvm, linux-kernel
On Mon, Jan 17, 2022, Like Xu wrote:
> From: Like Xu <likexu@tencent.com>
>
> XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by
> both RESET and INIT. In both cases, the size in bytes of the XSAVE
> area containing all states enabled by XCR0 or (XCRO | IA32_XSS)
> needs to be updated.
>
> Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
> Signed-off-by: Like Xu <likexu@tencent.com>
> ---
> arch/x86/kvm/x86.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 76b4803dd3bd..5748a57e1cb7 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -11134,6 +11134,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> struct kvm_cpuid_entry2 *cpuid_0x1;
> unsigned long old_cr0 = kvm_read_cr0(vcpu);
> unsigned long new_cr0;
> + bool need_update_cpuid = false;
>
> /*
> * Several of the "set" flows, e.g. ->set_cr0(), read other registers
> @@ -11199,6 +11200,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>
> vcpu->arch.msr_misc_features_enables = 0;
>
> + if (vcpu->arch.xcr0 != XFEATURE_MASK_FP)
> + need_update_cpuid = true;
> vcpu->arch.xcr0 = XFEATURE_MASK_FP;
> }
>
> @@ -11216,6 +11219,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
> kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
>
> + if (vcpu->arch.ia32_xss)
> + need_update_cpuid = true;
This means that kvm_set_msr_common()'s handling of MSR_IA32_XSS also needs to
update kvm_update_cpuid_runtime(). And then for bnoth XCR0 and XSS, I would very
strongly prefer that use the helpers to write the values and let the helpers call
kvm_update_cpuid_runtime(). Yes, that will mean kvm_update_cpuid_runtime() may be
called multiple times during INIT, but that's already true (CR4), and this isn't
exactly a fast path.
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 55518b7d3b96..22d4b1d15e94 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11256,7 +11256,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
vcpu->arch.msr_misc_features_enables = 0;
- vcpu->arch.xcr0 = XFEATURE_MASK_FP;
+ __kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP);
}
/* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */
@@ -11273,7 +11273,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
- vcpu->arch.ia32_xss = 0;
+ __kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true);
static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset
2022-01-18 18:30 ` [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset Sean Christopherson
@ 2022-01-19 7:25 ` Like Xu
0 siblings, 0 replies; 9+ messages in thread
From: Like Xu @ 2022-01-19 7:25 UTC (permalink / raw)
To: Sean Christopherson
Cc: Paolo Bonzini, Wanpeng Li, Jim Mattson, Vitaly Kuznetsov,
Joerg Roedel, kvm, linux-kernel
On 19/1/2022 2:30 am, Sean Christopherson wrote:
> On Mon, Jan 17, 2022, Like Xu wrote:
>> From: Like Xu <likexu@tencent.com>
>>
>> XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by
>> both RESET and INIT. In both cases, the size in bytes of the XSAVE
>> area containing all states enabled by XCR0 or (XCRO | IA32_XSS)
>> needs to be updated.
>>
>> Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
>> Signed-off-by: Like Xu <likexu@tencent.com>
>> ---
>> arch/x86/kvm/x86.c | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 76b4803dd3bd..5748a57e1cb7 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -11134,6 +11134,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>> struct kvm_cpuid_entry2 *cpuid_0x1;
>> unsigned long old_cr0 = kvm_read_cr0(vcpu);
>> unsigned long new_cr0;
>> + bool need_update_cpuid = false;
>>
>> /*
>> * Several of the "set" flows, e.g. ->set_cr0(), read other registers
>> @@ -11199,6 +11200,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>>
>> vcpu->arch.msr_misc_features_enables = 0;
>>
>> + if (vcpu->arch.xcr0 != XFEATURE_MASK_FP)
>> + need_update_cpuid = true;
>> vcpu->arch.xcr0 = XFEATURE_MASK_FP;
>> }
>>
>> @@ -11216,6 +11219,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>> cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
>> kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
>>
>> + if (vcpu->arch.ia32_xss)
>> + need_update_cpuid = true;
>
> This means that kvm_set_msr_common()'s handling of MSR_IA32_XSS also needs to
> update kvm_update_cpuid_runtime(). And then for bnoth XCR0 and XSS, I would very
> strongly prefer that use the helpers to write the values and let the helpers call
Looks good to me and let me apply it in the next version.
> kvm_update_cpuid_runtime(). Yes, that will mean kvm_update_cpuid_runtime() may be
> called multiple times during INIT, but that's already true (CR4), and this isn't
> exactly a fast path.
An undisclosed lazy mechanism is under analyzed for performance gains.
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 55518b7d3b96..22d4b1d15e94 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -11256,7 +11256,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>
> vcpu->arch.msr_misc_features_enables = 0;
>
> - vcpu->arch.xcr0 = XFEATURE_MASK_FP;
> + __kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP);
> }
>
> /* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */
> @@ -11273,7 +11273,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
> kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
>
> - vcpu->arch.ia32_xss = 0;
> + __kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true);
>
> static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v2] KVM: x86: Sync the states size with the XCR0/IA32_XSS at any time
2022-01-17 17:32 ` Paolo Bonzini
@ 2022-01-21 4:09 ` Like Xu
2022-01-21 15:41 ` Sean Christopherson
0 siblings, 1 reply; 9+ messages in thread
From: Like Xu @ 2022-01-21 4:09 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Wanpeng Li, Sean Christopherson, Jim Mattson, Vitaly Kuznetsov,
Joerg Roedel, kvm, linux-kernel
From: Like Xu <likexu@tencent.com>
XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by
both RESET and INIT. The kvm_set_msr_common()'s handling of MSR_IA32_XSS
also needs to update kvm_update_cpuid_runtime(). In the above cases, the
size in bytes of the XSAVE area containing all states enabled by XCR0 or
(XCRO | IA32_XSS) needs to be updated.
For simplicity and consistency, legacy helpers are used to write values
and call kvm_update_cpuid_runtime(), and it's not exactly a fast path.
Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
Signed-off-by: Like Xu <likexu@tencent.com>
---
v1 -> v2 Changelog:
- Strongly prefer that use the helpers to write the values; (Sean)
- Postpone IA32_XSS test cases once non-zero values are supported; (Paolo)
- User space may call SET_CPUID2 after kvm_vcpu_reset(init_event=false); (Paolo)
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 55518b7d3b96..22d4b1d15e94 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11256,7 +11256,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
vcpu->arch.msr_misc_features_enables = 0;
- vcpu->arch.xcr0 = XFEATURE_MASK_FP;
+ __kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP);
}
/* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */
@@ -11273,7 +11273,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
- vcpu->arch.ia32_xss = 0;
+ __kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true);
static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
--
2.33.1
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH v2] KVM: x86: Sync the states size with the XCR0/IA32_XSS at any time
2022-01-21 4:09 ` [PATCH v2] KVM: x86: Sync the states size with the XCR0/IA32_XSS at any time Like Xu
@ 2022-01-21 15:41 ` Sean Christopherson
2022-01-23 4:37 ` [PATCH v3] KVM: x86: Sync the states size with the XCR0/IA32_XSS at, " Like Xu
0 siblings, 1 reply; 9+ messages in thread
From: Sean Christopherson @ 2022-01-21 15:41 UTC (permalink / raw)
To: Like Xu
Cc: Paolo Bonzini, Wanpeng Li, Jim Mattson, Vitaly Kuznetsov,
Joerg Roedel, kvm, linux-kernel
On Fri, Jan 21, 2022, Like Xu wrote:
> From: Like Xu <likexu@tencent.com>
>
> XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by
> both RESET and INIT. The kvm_set_msr_common()'s handling of MSR_IA32_XSS
> also needs to update kvm_update_cpuid_runtime(). In the above cases, the
> size in bytes of the XSAVE area containing all states enabled by XCR0 or
> (XCRO | IA32_XSS) needs to be updated.
>
> For simplicity and consistency, legacy helpers are used to write values
s/legacy/existing
"legacy" refers to something that is outdated/deprecated, which isn't what you
intend here.
> and call kvm_update_cpuid_runtime(), and it's not exactly a fast path.
>
> Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
> Signed-off-by: Like Xu <likexu@tencent.com>
> ---
> v1 -> v2 Changelog:
> - Strongly prefer that use the helpers to write the values; (Sean)
> - Postpone IA32_XSS test cases once non-zero values are supported; (Paolo)
> - User space may call SET_CPUID2 after kvm_vcpu_reset(init_event=false); (Paolo)
>
> 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 55518b7d3b96..22d4b1d15e94 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -11256,7 +11256,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>
> vcpu->arch.msr_misc_features_enables = 0;
>
> - vcpu->arch.xcr0 = XFEATURE_MASK_FP;
> + __kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP);
> }
>
> /* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */
> @@ -11273,7 +11273,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
> kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
>
> - vcpu->arch.ia32_xss = 0;
> + __kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true);
This relies on a prep patch to invoke kvm_update_cpuid_runtime() in kvm_set_msr_common()
for MSR_IA32_XSS, no?
> static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
>
> --
> 2.33.1
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v3] KVM: x86: Sync the states size with the XCR0/IA32_XSS at, any time
2022-01-21 15:41 ` Sean Christopherson
@ 2022-01-23 4:37 ` Like Xu
2022-01-26 16:37 ` Sean Christopherson
0 siblings, 1 reply; 9+ messages in thread
From: Like Xu @ 2022-01-23 4:37 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Wanpeng Li, Jim Mattson, Vitaly Kuznetsov, Joerg Roedel, kvm,
linux-kernel, Sean Christopherson
From: Like Xu <likexu@tencent.com>
XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by
both RESET and INIT. The kvm_set_msr_common()'s handling of MSR_IA32_XSS
also needs to update kvm_update_cpuid_runtime(). In the above cases, the
size in bytes of the XSAVE area containing all states enabled by XCR0 or
(XCRO | IA32_XSS) needs to be updated.
For simplicity and consistency, existing helpers are used to write values
and call kvm_update_cpuid_runtime(), and it's not exactly a fast path.
Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
Signed-off-by: Like Xu <likexu@tencent.com>
---
v2 -> v3 Changelog:
- Apply s/legacy/existing in the commit message; (Sean)
- Invoke kvm_update_cpuid_runtime() for MSR_IA32_XSS; (Sean)
arch/x86/kvm/x86.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 55518b7d3b96..4b509b26d9ab 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3535,6 +3535,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct
msr_data *msr_info)
if (data & ~supported_xss)
return 1;
vcpu->arch.ia32_xss = data;
+ kvm_update_cpuid_runtime(vcpu);
break;
case MSR_SMI_COUNT:
if (!msr_info->host_initiated)
@@ -11256,7 +11257,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
vcpu->arch.msr_misc_features_enables = 0;
- vcpu->arch.xcr0 = XFEATURE_MASK_FP;
+ __kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP);
}
/* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */
@@ -11273,7 +11274,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
- vcpu->arch.ia32_xss = 0;
+ __kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true);
static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
--
2.33.1
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH v3] KVM: x86: Sync the states size with the XCR0/IA32_XSS at, any time
2022-01-23 4:37 ` [PATCH v3] KVM: x86: Sync the states size with the XCR0/IA32_XSS at, " Like Xu
@ 2022-01-26 16:37 ` Sean Christopherson
2022-01-26 17:08 ` Paolo Bonzini
0 siblings, 1 reply; 9+ messages in thread
From: Sean Christopherson @ 2022-01-26 16:37 UTC (permalink / raw)
To: Like Xu
Cc: Paolo Bonzini, Wanpeng Li, Jim Mattson, Vitaly Kuznetsov,
Joerg Roedel, kvm, linux-kernel
On Sun, Jan 23, 2022, Like Xu wrote:
> From: Like Xu <likexu@tencent.com>
>
> XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by
> both RESET and INIT. The kvm_set_msr_common()'s handling of MSR_IA32_XSS
> also needs to update kvm_update_cpuid_runtime(). In the above cases, the
> size in bytes of the XSAVE area containing all states enabled by XCR0 or
> (XCRO | IA32_XSS) needs to be updated.
>
> For simplicity and consistency, existing helpers are used to write values
> and call kvm_update_cpuid_runtime(), and it's not exactly a fast path.
>
> Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
> Signed-off-by: Like Xu <likexu@tencent.com>
> ---
> v2 -> v3 Changelog:
> - Apply s/legacy/existing in the commit message; (Sean)
> - Invoke kvm_update_cpuid_runtime() for MSR_IA32_XSS; (Sean)
>
> arch/x86/kvm/x86.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 55518b7d3b96..4b509b26d9ab 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3535,6 +3535,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct
> msr_data *msr_info)
> if (data & ~supported_xss)
> return 1;
> vcpu->arch.ia32_xss = data;
> + kvm_update_cpuid_runtime(vcpu);
> break;
> case MSR_SMI_COUNT:
> if (!msr_info->host_initiated)
> @@ -11256,7 +11257,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>
> vcpu->arch.msr_misc_features_enables = 0;
>
> - vcpu->arch.xcr0 = XFEATURE_MASK_FP;
> + __kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP);
> }
>
> /* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */
> @@ -11273,7 +11274,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
> kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
>
> - vcpu->arch.ia32_xss = 0;
> + __kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true);
Heh, this now conflicts with a patch Xiaoyao just posted, turns out the SDM was
wrong. I think there's also some whitespace change or something that prevents
this from applying cleanly. For convenience, I'll post a miniseries with this
and Xiaoyao's patch.
[*] https://lore.kernel.org/all/20220126034750.2495371-1-xiaoyao.li@intel.com
>
> static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
>
> --
> 2.33.1
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v3] KVM: x86: Sync the states size with the XCR0/IA32_XSS at, any time
2022-01-26 16:37 ` Sean Christopherson
@ 2022-01-26 17:08 ` Paolo Bonzini
0 siblings, 0 replies; 9+ messages in thread
From: Paolo Bonzini @ 2022-01-26 17:08 UTC (permalink / raw)
To: Sean Christopherson, Like Xu
Cc: Wanpeng Li, Jim Mattson, Vitaly Kuznetsov, Joerg Roedel, kvm,
linux-kernel
On 1/26/22 17:37, Sean Christopherson wrote:
> On Sun, Jan 23, 2022, Like Xu wrote:
>> From: Like Xu <likexu@tencent.com>
>>
>> XCR0 is reset to 1 by RESET but not INIT and IA32_XSS is zeroed by
>> both RESET and INIT. The kvm_set_msr_common()'s handling of MSR_IA32_XSS
>> also needs to update kvm_update_cpuid_runtime(). In the above cases, the
>> size in bytes of the XSAVE area containing all states enabled by XCR0 or
>> (XCRO | IA32_XSS) needs to be updated.
>>
>> For simplicity and consistency, existing helpers are used to write values
>> and call kvm_update_cpuid_runtime(), and it's not exactly a fast path.
>>
>> Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT")
>> Signed-off-by: Like Xu <likexu@tencent.com>
>> ---
>> v2 -> v3 Changelog:
>> - Apply s/legacy/existing in the commit message; (Sean)
>> - Invoke kvm_update_cpuid_runtime() for MSR_IA32_XSS; (Sean)
>>
>> arch/x86/kvm/x86.c | 5 +++--
>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 55518b7d3b96..4b509b26d9ab 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -3535,6 +3535,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct
>> msr_data *msr_info)
>> if (data & ~supported_xss)
>> return 1;
>> vcpu->arch.ia32_xss = data;
>> + kvm_update_cpuid_runtime(vcpu);
>> break;
>> case MSR_SMI_COUNT:
>> if (!msr_info->host_initiated)
>> @@ -11256,7 +11257,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>>
>> vcpu->arch.msr_misc_features_enables = 0;
>>
>> - vcpu->arch.xcr0 = XFEATURE_MASK_FP;
>> + __kvm_set_xcr(vcpu, 0, XFEATURE_MASK_FP);
>> }
>>
>> /* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */
>> @@ -11273,7 +11274,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>> cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0);
>> kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);
>>
>> - vcpu->arch.ia32_xss = 0;
>> + __kvm_set_msr(vcpu, MSR_IA32_XSS, 0, true);
>
> Heh, this now conflicts with a patch Xiaoyao just posted, turns out the SDM was
> wrong. I think there's also some whitespace change or something that prevents
> this from applying cleanly. For convenience, I'll post a miniseries with this
> and Xiaoyao's patch.
>
> [*] https://lore.kernel.org/all/20220126034750.2495371-1-xiaoyao.li@intel.com
It's okay, fixing the conflict in Xiaoyao's patch is trivial
and---anyway---KVM does not support XSS != 0 for now so his patch
doesn't really have any practical effect.
Like's patch queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2022-01-26 17:08 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-01-17 8:26 [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset Like Xu
2022-01-17 17:32 ` Paolo Bonzini
2022-01-21 4:09 ` [PATCH v2] KVM: x86: Sync the states size with the XCR0/IA32_XSS at any time Like Xu
2022-01-21 15:41 ` Sean Christopherson
2022-01-23 4:37 ` [PATCH v3] KVM: x86: Sync the states size with the XCR0/IA32_XSS at, " Like Xu
2022-01-26 16:37 ` Sean Christopherson
2022-01-26 17:08 ` Paolo Bonzini
2022-01-18 18:30 ` [PATCH] KVM: x86: Update the states size cpuid even if XCR0/IA32_XSS is reset Sean Christopherson
2022-01-19 7:25 ` Like Xu
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.