From: Paolo Bonzini <pbonzini@redhat.com>
To: Yang Weijiang <weijiang.yang@intel.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
sean.j.christopherson@intel.com, jmattson@google.com
Cc: yu.c.zhang@linux.intel.com
Subject: Re: [PATCH v14 11/13] KVM: VMX: Pass through CET MSRs to the guest when supported
Date: Thu, 28 Jan 2021 19:04:06 +0100 [thread overview]
Message-ID: <e383a377-ee64-342d-b1dd-0f99186714e3@redhat.com> (raw)
In-Reply-To: <78948a28-2b6c-fccb-971a-550ea7e4da2c@redhat.com>
On 28/01/21 18:54, Paolo Bonzini wrote:
> On 06/11/20 02:16, Yang Weijiang wrote:
>> Pass through all CET MSRs when the associated CET component (kernel vs.
>> user) is enabled to improve guest performance. All CET MSRs are context
>> switched, either via dedicated VMCS fields or XSAVES.
>>
>> Co-developed-by: Zhang Yi Z <yi.z.zhang@linux.intel.com>
>> Signed-off-by: Zhang Yi Z <yi.z.zhang@linux.intel.com>
>> Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
>> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
>> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
>> ---
>> arch/x86/kvm/vmx/vmx.c | 29 +++++++++++++++++++++++++++++
>> 1 file changed, 29 insertions(+)
>>
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> index c88a6e1721b1..6ba2027a3d44 100644
>> --- a/arch/x86/kvm/vmx/vmx.c
>> +++ b/arch/x86/kvm/vmx/vmx.c
>> @@ -7366,6 +7366,32 @@ static void update_intel_pt_cfg(struct kvm_vcpu
>> *vcpu)
>> vmx->pt_desc.ctl_bitmask &= ~(0xfULL << (32 + i * 4));
>> }
>> +static bool is_cet_state_supported(struct kvm_vcpu *vcpu, u32 xss_state)
>> +{
>> + return (vcpu->arch.guest_supported_xss & xss_state) &&
>> + (guest_cpuid_has(vcpu, X86_FEATURE_SHSTK) ||
>> + guest_cpuid_has(vcpu, X86_FEATURE_IBT));
>> +}
>> +
>> +static void vmx_update_intercept_for_cet_msr(struct kvm_vcpu *vcpu)
>> +{
>> + bool incpt = !is_cet_state_supported(vcpu, XFEATURE_MASK_CET_USER);
>> +
>> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_U_CET, MSR_TYPE_RW, incpt);
>> +
>> + incpt |= !guest_cpuid_has(vcpu, X86_FEATURE_SHSTK);
>> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_PL3_SSP, MSR_TYPE_RW,
>> incpt);
>> +
>> + incpt = !is_cet_state_supported(vcpu, XFEATURE_MASK_CET_KERNEL);
>> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_S_CET, MSR_TYPE_RW, incpt);
>> +
>> + incpt |= !guest_cpuid_has(vcpu, X86_FEATURE_SHSTK);
>> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_INT_SSP_TAB,
>> MSR_TYPE_RW, incpt);
>> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_PL0_SSP, MSR_TYPE_RW,
>> incpt);
>> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_PL1_SSP, MSR_TYPE_RW,
>> incpt);
>> + vmx_set_intercept_for_msr(vcpu, MSR_IA32_PL2_SSP, MSR_TYPE_RW,
>> incpt);
>> +}
>> +
>> static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
>> {
>> struct vcpu_vmx *vmx = to_vmx(vcpu);
>> @@ -7409,6 +7435,9 @@ static void vmx_vcpu_after_set_cpuid(struct
>> kvm_vcpu *vcpu)
>> /* Refresh #PF interception to account for MAXPHYADDR changes. */
>> update_exception_bitmap(vcpu);
>> +
>> + if (kvm_cet_supported())
>> + vmx_update_intercept_for_cet_msr(vcpu);
>> }
>> static __init void vmx_set_cpu_caps(void)
>>
>
> Can you do this only if CR4.CET=1?
Actually, considering this is XSAVES and not RDMSR/WRMSR state, this is
okay as is.
Paolo
next prev parent reply other threads:[~2021-01-28 18:15 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-06 1:16 [PATCH v14 00/13] Introduce support for guest CET feature Yang Weijiang
2020-11-06 1:16 ` [PATCH v14 01/13] KVM: x86: Report XSS as an MSR to be saved if there are supported features Yang Weijiang
2020-11-06 1:16 ` [PATCH v14 02/13] KVM: x86: Refresh CPUID on writes to MSR_IA32_XSS Yang Weijiang
2020-11-06 1:16 ` [PATCH v14 03/13] KVM: x86: Add #CP support in guest exception dispatch Yang Weijiang
2020-11-06 1:16 ` [PATCH v14 04/13] KVM: VMX: Introduce CET VMCS fields and flags Yang Weijiang
2020-11-06 1:16 ` [PATCH v14 05/13] KVM: x86: Add fault checks for CR4.CET Yang Weijiang
2020-11-09 10:44 ` kernel test robot
2020-11-06 1:16 ` [PATCH v14 06/13] KVM: x86: Load guest fpu state when accessing MSRs managed by XSAVES Yang Weijiang
2020-11-06 1:16 ` [PATCH v14 07/13] KVM: VMX: Emulate reads and writes to CET MSRs Yang Weijiang
2021-01-28 17:45 ` Paolo Bonzini
2021-01-29 8:07 ` Yang Weijiang
2020-11-06 1:16 ` [PATCH v14 08/13] KVM: VMX: Add a synthetic MSR to allow userspace VMM to access GUEST_SSP Yang Weijiang
2021-01-28 17:41 ` Paolo Bonzini
2021-01-28 17:42 ` Paolo Bonzini
2020-11-06 1:16 ` [PATCH v14 09/13] KVM: x86: Report CET MSRs as to-be-saved if CET is supported Yang Weijiang
2020-11-09 6:17 ` kernel test robot
2021-01-28 17:46 ` Paolo Bonzini
2021-01-29 8:08 ` Yang Weijiang
2020-11-06 1:16 ` [PATCH v14 10/13] KVM: x86: Enable CET virtualization for VMX and advertise CET to userspace Yang Weijiang
2020-11-09 7:23 ` kernel test robot
2021-01-28 17:53 ` Paolo Bonzini
[not found] ` <20210129112437.GA29715@local-michael-cet-test.sh.intel.com>
[not found] ` <68e288ee-6e09-36f1-a6c9-bed864eb7678@redhat.com>
[not found] ` <20210129121717.GA30243@local-michael-cet-test.sh.intel.com>
[not found] ` <1cf7e501-2c69-8b76-9332-42db1348ab08@redhat.com>
2021-01-30 6:32 ` Yang Weijiang
2021-02-01 4:56 ` Yang Weijiang
2020-11-06 1:16 ` [PATCH v14 11/13] KVM: VMX: Pass through CET MSRs to the guest when supported Yang Weijiang
2021-01-28 17:54 ` Paolo Bonzini
2021-01-28 18:04 ` Paolo Bonzini [this message]
2020-11-06 1:16 ` [PATCH v14 12/13] KVM: nVMX: Add helper to check the vmcs01 MSR bitmap for MSR pass-through Yang Weijiang
2020-11-06 1:16 ` [PATCH v14 13/13] KVM: nVMX: Enable CET support for nested VMX Yang Weijiang
2021-01-28 17:57 ` [PATCH v14 00/13] Introduce support for guest CET feature Paolo Bonzini
2021-01-28 18:04 ` Sean Christopherson
2021-01-28 18:06 ` Paolo Bonzini
2021-01-28 18:24 ` Sean Christopherson
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