From: "Yang, Weijiang" <weijiang.yang@intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: <pbonzini@redhat.com>, <peterz@infradead.org>,
<john.allen@amd.com>, <kvm@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <rick.p.edgecombe@intel.com>,
<chao.gao@intel.com>, <binbin.wu@linux.intel.com>
Subject: Re: [PATCH v5 05/19] KVM:x86: Initialize kvm_caps.supported_xss
Date: Tue, 8 Aug 2023 23:08:00 +0800 [thread overview]
Message-ID: <9fa7222b-311d-a00b-29e5-15e1a7d241ea@intel.com> (raw)
In-Reply-To: <ZM1HODB6No0XArEq@google.com>
On 8/5/2023 2:45 AM, Sean Christopherson wrote:
> On Thu, Aug 03, 2023, Yang Weijiang wrote:
>> Set kvm_caps.supported_xss to host_xss && KVM XSS mask.
>> host_xss contains the host supported xstate feature bits for thread
>> context switch, KVM_SUPPORTED_XSS includes all KVM enabled XSS feature
>> bits, the operation result represents all KVM supported feature bits.
>> Since the result is subset of host_xss, the related XSAVE-managed MSRs
>> are automatically swapped for guest and host when vCPU exits to
>> userspace.
>>
>> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
>> ---
>> arch/x86/kvm/vmx/vmx.c | 1 -
>> arch/x86/kvm/x86.c | 6 +++++-
>> 2 files changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> index 0ecf4be2c6af..c8d9870cfecb 100644
>> --- a/arch/x86/kvm/vmx/vmx.c
>> +++ b/arch/x86/kvm/vmx/vmx.c
>> @@ -7849,7 +7849,6 @@ static __init void vmx_set_cpu_caps(void)
>> kvm_cpu_cap_set(X86_FEATURE_UMIP);
>>
>> /* CPUID 0xD.1 */
>> - kvm_caps.supported_xss = 0;
> Dropping this code in *this* patch is wrong, this belong in whatever patch(es) adds
> IBT and SHSTK support in VMX.
>
> And that does matter because it means this common patch can be carried wih SVM
> support without breaking VMX.
OK, I'll dropping this line for VMX/SVM in CET feature bits enabling patch.
>> if (!cpu_has_vmx_xsaves())
>> kvm_cpu_cap_clear(X86_FEATURE_XSAVES);
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 5d6d6fa33e5b..e9f3627d5fdd 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -225,6 +225,8 @@ static struct kvm_user_return_msrs __percpu *user_return_msrs;
>> | XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 \
>> | XFEATURE_MASK_PKRU | XFEATURE_MASK_XTILE)
>>
>> +#define KVM_SUPPORTED_XSS 0
>> +
>> u64 __read_mostly host_efer;
>> EXPORT_SYMBOL_GPL(host_efer);
>>
>> @@ -9498,8 +9500,10 @@ static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
>>
>> rdmsrl_safe(MSR_EFER, &host_efer);
>>
>> - if (boot_cpu_has(X86_FEATURE_XSAVES))
>> + if (boot_cpu_has(X86_FEATURE_XSAVES)) {
>> rdmsrl(MSR_IA32_XSS, host_xss);
>> + kvm_caps.supported_xss = host_xss & KVM_SUPPORTED_XSS;
>> + }
> Can you opportunistically (in this patch) hoist this above EFER so that XCR0 and
> XSS are colocated? I.e. end up with this:
>
> if (boot_cpu_has(X86_FEATURE_XSAVE)) {
> host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
> kvm_caps.supported_xcr0 = host_xcr0 & KVM_SUPPORTED_XCR0;
> }
> if (boot_cpu_has(X86_FEATURE_XSAVES)) {
> rdmsrl(MSR_IA32_XSS, host_xss);
> kvm_caps.supported_xss = host_xss & KVM_SUPPORTED_XSS;
> }
>
> rdmsrl_safe(MSR_EFER, &host_efer);
Will change it, thanks!
next prev parent reply other threads:[~2023-08-08 16:00 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-03 4:27 [PATCH v5 00/19] Enable CET Virtualization Yang Weijiang
2023-08-03 4:27 ` [PATCH v5 01/19] x86/cpufeatures: Add CPU feature flags for shadow stacks Yang Weijiang
2023-08-03 4:27 ` [PATCH v5 02/19] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yang Weijiang
2023-08-03 4:27 ` [PATCH v5 03/19] KVM:x86: Report XSS as to-be-saved if there are supported features Yang Weijiang
2023-08-03 4:27 ` [PATCH v5 04/19] KVM:x86: Refresh CPUID on write to guest MSR_IA32_XSS Yang Weijiang
2023-08-04 16:02 ` Sean Christopherson
2023-08-04 21:43 ` Paolo Bonzini
2023-08-09 3:11 ` Yang, Weijiang
2023-08-08 14:20 ` Yang, Weijiang
2023-08-04 18:27 ` Sean Christopherson
2023-08-07 6:55 ` Paolo Bonzini
2023-08-09 8:56 ` Yang, Weijiang
2023-08-10 0:01 ` Paolo Bonzini
2023-08-10 1:12 ` Yang, Weijiang
2023-08-03 4:27 ` [PATCH v5 05/19] KVM:x86: Initialize kvm_caps.supported_xss Yang Weijiang
2023-08-04 18:45 ` Sean Christopherson
2023-08-08 15:08 ` Yang, Weijiang [this message]
2023-08-03 4:27 ` [PATCH v5 06/19] KVM:x86: Load guest FPU state when access XSAVE-managed MSRs Yang Weijiang
2023-08-03 4:27 ` [PATCH v5 07/19] KVM:x86: Add fault checks for guest CR4.CET setting Yang Weijiang
2023-08-03 9:07 ` Chao Gao
2023-08-03 4:27 ` [PATCH v5 08/19] KVM:x86: Report KVM supported CET MSRs as to-be-saved Yang Weijiang
2023-08-03 10:39 ` Chao Gao
2023-08-04 3:13 ` Yang, Weijiang
2023-08-04 5:51 ` Chao Gao
2023-08-04 18:51 ` Sean Christopherson
2023-08-04 22:01 ` Paolo Bonzini
2023-08-08 15:16 ` Yang, Weijiang
2023-08-06 8:54 ` Yang, Weijiang
2023-08-04 18:55 ` Sean Christopherson
2023-08-08 15:26 ` Yang, Weijiang
2023-08-04 21:47 ` Paolo Bonzini
2023-08-09 3:14 ` Yang, Weijiang
2023-08-03 4:27 ` [PATCH v5 09/19] KVM:x86: Make guest supervisor states as non-XSAVE managed Yang Weijiang
2023-08-03 11:15 ` Chao Gao
2023-08-04 3:26 ` Yang, Weijiang
2023-08-04 20:45 ` Sean Christopherson
2023-08-04 20:59 ` Peter Zijlstra
2023-08-04 21:32 ` Paolo Bonzini
2023-08-09 2:51 ` Yang, Weijiang
2023-08-09 2:39 ` Yang, Weijiang
2023-08-10 9:29 ` Yang, Weijiang
2023-08-10 14:29 ` Dave Hansen
2023-08-10 15:15 ` Paolo Bonzini
2023-08-10 15:37 ` Sean Christopherson
2023-08-11 3:03 ` Yang, Weijiang
2023-08-28 21:00 ` Dave Hansen
2023-08-29 7:05 ` Yang, Weijiang
2023-08-03 4:27 ` [PATCH v5 10/19] KVM:VMX: Introduce CET VMCS fields and control bits Yang Weijiang
2023-08-03 4:27 ` [PATCH v5 11/19] KVM:VMX: Emulate read and write to CET MSRs Yang Weijiang
2023-08-04 5:14 ` Chao Gao
2023-08-04 21:27 ` Sean Christopherson
2023-08-04 21:45 ` Paolo Bonzini
2023-08-04 22:21 ` Sean Christopherson
2023-08-07 7:03 ` Paolo Bonzini
2023-08-06 8:44 ` Yang, Weijiang
2023-08-07 7:00 ` Paolo Bonzini
2023-08-04 8:28 ` Chao Gao
2023-08-09 7:12 ` Yang, Weijiang
2023-08-04 21:40 ` Paolo Bonzini
2023-08-09 3:05 ` Yang, Weijiang
2023-08-03 4:27 ` [PATCH v5 12/19] KVM:x86: Save and reload SSP to/from SMRAM Yang Weijiang
2023-08-04 7:53 ` Chao Gao
2023-08-04 15:25 ` Sean Christopherson
2023-08-06 9:14 ` Yang, Weijiang
2023-08-03 4:27 ` [PATCH v5 13/19] KVM:VMX: Set up interception for CET MSRs Yang Weijiang
2023-08-04 8:16 ` Chao Gao
2023-08-06 9:22 ` Yang, Weijiang
2023-08-07 1:16 ` Chao Gao
2023-08-09 6:11 ` Yang, Weijiang
2023-08-03 4:27 ` [PATCH v5 14/19] KVM:VMX: Set host constant supervisor states to VMCS fields Yang Weijiang
2023-08-04 8:23 ` Chao Gao
2023-08-03 4:27 ` [PATCH v5 15/19] KVM:x86: Optimize CET supervisor SSP save/reload Yang Weijiang
2023-08-04 8:43 ` Chao Gao
2023-08-09 9:00 ` Yang, Weijiang
2023-08-03 4:27 ` [PATCH v5 16/19] KVM:x86: Enable CET virtualization for VMX and advertise to userspace Yang Weijiang
2023-08-03 4:27 ` [PATCH v5 17/19] KVM:x86: Enable guest CET supervisor xstate bit support Yang Weijiang
2023-08-04 22:02 ` Paolo Bonzini
2023-08-09 6:07 ` Yang, Weijiang
2023-08-03 4:27 ` [PATCH v5 18/19] KVM:nVMX: Refine error code injection to nested VM Yang Weijiang
2023-08-04 21:38 ` Sean Christopherson
2023-08-09 3:00 ` Yang, Weijiang
2023-08-03 4:27 ` [PATCH v5 19/19] KVM:nVMX: Enable CET support for " Yang Weijiang
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