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From: "Yang, Weijiang" <weijiang.yang@intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: <pbonzini@redhat.com>, <jmattson@google.com>,
	<kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<like.xu.linux@gmail.com>, <kan.liang@linux.intel.com>,
	<wei.w.wang@intel.com>
Subject: Re: [PATCH v2 03/15] KVM: x86: Refresh CPUID on writes to MSR_IA32_XSS
Date: Mon, 30 Jan 2023 14:33:28 +0800	[thread overview]
Message-ID: <4e6dec2b-29af-7772-0427-a3c28cb2ab52@intel.com> (raw)
In-Reply-To: <Y9LZhsqxRjMjbK3s@google.com>


On 1/27/2023 3:50 AM, Sean Christopherson wrote:
> On Thu, Nov 24, 2022, Yang Weijiang wrote:
>> Updated CPUID.0xD.0x1, which reports the current required storage size
>> of all features enabled via XCR0 | XSS, when the guest's XSS is modified.
>>
>> Note, KVM does not yet support any XSS based features, i.e. supported_xss
>> is guaranteed to be zero at this time.
>>
>> Co-developed-by: Zhang Yi Z <yi.z.zhang@linux.intel.com>
>> Signed-off-by: Zhang Yi Z <yi.z.zhang@linux.intel.com>
>> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
>> ---
>>   arch/x86/kvm/cpuid.c | 16 +++++++++++++---
>>   arch/x86/kvm/x86.c   |  6 ++++--
>>   2 files changed, 17 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
>> index 6b5912578edd..85e3df6217af 100644
>> --- a/arch/x86/kvm/cpuid.c
>> +++ b/arch/x86/kvm/cpuid.c
>> @@ -272,9 +272,19 @@ static void __kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu, struct kvm_cpuid_e
>>   		best->ebx = xstate_required_size(vcpu->arch.xcr0, false);
>>   
>>   	best = cpuid_entry2_find(entries, nent, 0xD, 1);
>> -	if (best && (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||
>> -		     cpuid_entry_has(best, X86_FEATURE_XSAVEC)))
>> -		best->ebx = xstate_required_size(vcpu->arch.xcr0, true);
>> +	if (best) {
>> +		if (cpuid_entry_has(best, X86_FEATURE_XSAVES) ||
>> +		    cpuid_entry_has(best, X86_FEATURE_XSAVEC))  {
>> +			u64 xstate = vcpu->arch.xcr0 | vcpu->arch.ia32_xss;
>> +
>> +			best->ebx = xstate_required_size(xstate, true);
>> +		}
>> +
>> +		if (!cpuid_entry_has(best, X86_FEATURE_XSAVES)) {
>> +			best->ecx = 0;
>> +			best->edx = 0;
> ECX and EDX should be left alone, it is userspace's responsibility to provide a
> sane CPUID model.  E.g. KVM doesn't clear EBX or EDX in CPUID.0xD.0x1 when XSAVE
> is unsupported.


Thanks for review!

Sure, I'll remove it.



>
>> +		}
>> +	}
>>   
>>   	best = __kvm_find_kvm_cpuid_features(vcpu, entries, nent);
>>   	if (kvm_hlt_in_guest(vcpu->kvm) && best &&
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 16726b44061b..888a153e32bc 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -3685,8 +3685,10 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>>   		 */
>>   		if (data & ~kvm_caps.supported_xss)
>>   			return 1;
>> -		vcpu->arch.ia32_xss = data;
>> -		kvm_update_cpuid_runtime(vcpu);
>> +		if (vcpu->arch.ia32_xss != data) {
>> +			vcpu->arch.ia32_xss = data;
>> +			kvm_update_cpuid_runtime(vcpu);
>> +		}
>>   		break;
>>   	case MSR_SMI_COUNT:
>>   		if (!msr_info->host_initiated)
>> -- 
>> 2.27.0
>>

  reply	other threads:[~2023-01-30  6:33 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-25  4:05 [PATCH v2 00/15] Introduce Architectural LBR for vPMU Yang Weijiang
2022-11-25  4:05 ` [PATCH v2 01/15] perf/x86/lbr: Simplify the exposure check for the LBR_INFO registers Yang Weijiang
2022-12-22 10:57   ` Like Xu
2022-12-22 13:29     ` Peter Zijlstra
2022-12-22 17:41     ` Sean Christopherson
2022-12-23  2:12       ` Like Xu
2022-12-27 11:58   ` [tip: perf/core] " tip-bot2 for Like Xu
2022-11-25  4:05 ` [PATCH v2 02/15] KVM: x86: Report XSS as an MSR to be saved if there are supported features Yang Weijiang
2022-11-25  4:05 ` [PATCH v2 03/15] KVM: x86: Refresh CPUID on writes to MSR_IA32_XSS Yang Weijiang
2023-01-26 19:50   ` Sean Christopherson
2023-01-30  6:33     ` Yang, Weijiang [this message]
2022-11-25  4:05 ` [PATCH v2 04/15] KVM: PMU: disable LBR handling if architectural LBR is available Yang Weijiang
2023-01-27 20:10   ` Sean Christopherson
2023-01-30  8:10     ` Yang, Weijiang
2022-11-25  4:05 ` [PATCH v2 05/15] KVM: vmx/pmu: Emulate MSR_ARCH_LBR_DEPTH for guest Arch LBR Yang Weijiang
2022-12-22 11:00   ` Like Xu
2022-12-25  4:30     ` Yang, Weijiang
2022-12-22 11:15   ` Like Xu
2023-01-27 20:25   ` Sean Christopherson
2023-01-30 11:46     ` Yang, Weijiang
2022-11-25  4:05 ` [PATCH v2 06/15] KVM: vmx/pmu: Emulate MSR_ARCH_LBR_CTL " Yang Weijiang
2022-12-22 11:09   ` Like Xu
2022-12-25  4:27     ` Yang, Weijiang
2022-12-22 11:19   ` Like Xu
2022-12-25  4:16     ` Yang, Weijiang
2022-12-22 11:24   ` Like Xu
2022-12-25  4:08     ` Yang, Weijiang
2023-01-27 21:42   ` Sean Christopherson
2022-11-25  4:05 ` [PATCH v2 07/15] KVM: VMX: Support passthrough of architectural LBRs Yang Weijiang
2022-11-25  4:05 ` [PATCH v2 08/15] KVM: x86: Add Arch LBR MSRs to msrs_to_save_all list Yang Weijiang
2023-01-27 21:43   ` Sean Christopherson
2023-01-30 12:27     ` Yang, Weijiang
2022-11-25  4:05 ` [PATCH v2 09/15] KVM: x86: Refine the matching and clearing logic for supported_xss Yang Weijiang
2023-01-27 21:46   ` Sean Christopherson
2023-01-30 12:37     ` Yang, Weijiang
2022-11-25  4:05 ` [PATCH v2 10/15] KVM: x86/vmx: Check Arch LBR config when return perf capabilities Yang Weijiang
2022-12-22 11:06   ` Like Xu
2022-12-25  4:28     ` Yang, Weijiang
2023-01-27 22:04   ` Sean Christopherson
2022-11-25  4:06 ` [PATCH v2 11/15] KVM: x86: Add XSAVE Support for Architectural LBR Yang Weijiang
2023-01-27 22:07   ` Sean Christopherson
2023-01-30 13:13     ` Yang, Weijiang
2022-11-25  4:06 ` [PATCH v2 12/15] KVM: x86/vmx: Disable Arch LBREn bit in #DB and warm reset Yang Weijiang
2022-12-22 11:22   ` Like Xu
2022-12-25  4:12     ` Yang, Weijiang
2023-01-27 22:09   ` Sean Christopherson
2023-01-30 13:09     ` Yang, Weijiang
2022-11-25  4:06 ` [PATCH v2 13/15] KVM: x86/vmx: Save/Restore guest Arch LBR Ctrl msr at SMM entry/exit Yang Weijiang
2023-01-27 22:11   ` Sean Christopherson
2023-01-30 12:50     ` Yang, Weijiang
2022-11-25  4:06 ` [PATCH v2 14/15] KVM: x86: Add Arch LBR data MSR access interface Yang Weijiang
2023-01-27 22:13   ` Sean Christopherson
2023-01-30 12:46     ` Yang, Weijiang
2023-01-30 17:30       ` Sean Christopherson
2023-01-31 13:14         ` Yang, Weijiang
2023-01-31 16:05           ` Sean Christopherson
2022-11-25  4:06 ` [PATCH v2 15/15] KVM: x86/cpuid: Advertise Arch LBR feature in CPUID Yang Weijiang
2022-12-22 11:03   ` Like Xu
2022-12-25  4:31     ` Yang, Weijiang
2023-01-27 22:15   ` Sean Christopherson
2023-01-12  1:57 ` [PATCH v2 00/15] Introduce Architectural LBR for vPMU Yang, Weijiang
2023-01-27 22:46 ` Sean Christopherson
2023-01-30 13:38   ` Yang, Weijiang
2023-06-05  9:50   ` Like Xu

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