From: Sean Christopherson <seanjc@google.com>
To: Chenyi Qiang <chenyi.qiang@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Xiaoyao Li <xiaoyao.li@intel.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 6/7] KVM: VMX: Expose PKS to guest
Date: Mon, 8 Nov 2021 21:31:39 +0000 [thread overview]
Message-ID: <YYmXO2WQpydWVro0@google.com> (raw)
In-Reply-To: <20210811101126.8973-7-chenyi.qiang@intel.com>
On Wed, Aug 11, 2021, Chenyi Qiang wrote:
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 739be5da3bca..dbee0d639db3 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -458,7 +458,7 @@ void kvm_set_cpu_caps(void)
> F(AVX512_VPOPCNTDQ) | F(UMIP) | F(AVX512_VBMI2) | F(GFNI) |
> F(VAES) | F(VPCLMULQDQ) | F(AVX512_VNNI) | F(AVX512_BITALG) |
> F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | 0 /*WAITPKG*/ |
> - F(SGX_LC) | F(BUS_LOCK_DETECT)
> + F(SGX_LC) | F(BUS_LOCK_DETECT) | 0 /*PKS*/
...
> );
> /* Set LA57 based on hardware capability. */
> if (cpuid_ecx(7) & F(LA57))
...
> @@ -7311,6 +7312,14 @@ static __init void vmx_set_cpu_caps(void)
>
> if (cpu_has_vmx_waitpkg())
> kvm_cpu_cap_check_and_set(X86_FEATURE_WAITPKG);
> +
> + /*
> + * PKS is not yet implemented for shadow paging.
> + * If not support VM_{ENTRY, EXIT}_LOAD_IA32_PKRS,
> + * don't expose the PKS as well.
> + */
> + if (enable_ept && cpu_has_load_ia32_pkrs())
> + kvm_cpu_cap_check_and_set(X86_FEATURE_PKS);
I would rather handle the !TDP case in cpuid.c alongside the PKU. The decision
to not support Protection Keys with legacy shadow paging is an x86 decision, not
a VMX decision.
And VMX's extra restriction on the VMCS support should not bleed into common x86.
Can you also opportunistically update the comment (see below) to explain _why_
OSPKE needs to be enabled in order to advertise PKU?
Thanks!
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 2d70edb0f323..c4ed6881857c 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -439,18 +439,23 @@ void kvm_set_cpu_caps(void)
F(AVX512_VPOPCNTDQ) | F(UMIP) | F(AVX512_VBMI2) | F(GFNI) |
F(VAES) | F(VPCLMULQDQ) | F(AVX512_VNNI) | F(AVX512_BITALG) |
F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | 0 /*WAITPKG*/ |
- F(SGX_LC) | F(BUS_LOCK_DETECT)
+ F(SGX_LC) | F(BUS_LOCK_DETECT) | F(PKS)
);
/* Set LA57 based on hardware capability. */
if (cpuid_ecx(7) & F(LA57))
kvm_cpu_cap_set(X86_FEATURE_LA57);
/*
- * PKU not yet implemented for shadow paging and requires OSPKE
- * to be set on the host. Clear it if that is not the case
+ * Protection Keys are not supported for shadow paging. PKU further
+ * requires OSPKE to be set on the host in order to use {RD,WR}PKRU to
+ * save/restore the guests PKRU.
*/
- if (!tdp_enabled || !boot_cpu_has(X86_FEATURE_OSPKE))
+ if (!tdp_enabled) {
kvm_cpu_cap_clear(X86_FEATURE_PKU);
+ kvm_cpu_cap_clear(X86_FEATURE_PKS);
+ } else if (!boot_cpu_has(X86_FEATURE_OSPKE)) {
+ kvm_cpu_cap_clear(X86_FEATURE_PKU);
+ }
kvm_cpu_cap_mask(CPUID_7_EDX,
F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) |
and then vmx.c only needs to handle clearing PKS when the VMCS controls aren't
available.
next prev parent reply other threads:[~2021-11-08 21:31 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-11 10:11 [PATCH v5 0/7] KVM: PKS Virtualization support Chenyi Qiang
2021-08-11 10:11 ` [PATCH v5 1/7] KVM: VMX: Introduce PKS VMCS fields Chenyi Qiang
2021-08-11 10:11 ` [PATCH v5 2/7] KVM: VMX: Add proper cache tracking for PKRS Chenyi Qiang
2021-11-08 17:13 ` Sean Christopherson
2021-11-08 18:07 ` Sean Christopherson
2021-08-11 10:11 ` [PATCH v5 3/7] KVM: X86: Expose IA32_PKRS MSR Chenyi Qiang
2021-11-08 17:44 ` Sean Christopherson
2021-11-09 5:54 ` Chenyi Qiang
2021-11-09 15:30 ` Sean Christopherson
2021-11-10 0:56 ` Chenyi Qiang
2021-11-08 20:18 ` Sean Christopherson
2021-08-11 10:11 ` [PATCH v5 4/7] KVM: MMU: Rename the pkru to pkr Chenyi Qiang
2021-08-11 10:11 ` [PATCH v5 5/7] KVM: MMU: Add support for PKS emulation Chenyi Qiang
2021-11-08 19:46 ` Sean Christopherson
2021-11-09 6:42 ` Chenyi Qiang
2021-11-08 19:52 ` Sean Christopherson
2021-08-11 10:11 ` [PATCH v5 6/7] KVM: VMX: Expose PKS to guest Chenyi Qiang
2021-11-08 21:31 ` Sean Christopherson [this message]
2021-08-11 10:11 ` [PATCH v5 7/7] KVM: VMX: Enable PKS for nested VM Chenyi Qiang
2021-08-26 2:04 ` [PATCH v5 0/7] KVM: PKS Virtualization support Chenyi Qiang
2021-10-25 15:12 ` Paolo Bonzini
2021-10-26 3:14 ` Chenyi Qiang
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