From: Maxim Levitsky <mlevitsk@redhat.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Xiaoyao Li <xiaoyao.li@intel.com>,
Reiji Watanabe <reijiw@google.com>
Subject: Re: [PATCH 07/15] KVM: x86: Add support for RDPID without RDTSCP
Date: Mon, 10 May 2021 11:20:45 +0300 [thread overview]
Message-ID: <3699a28f75fbb541ab14e90d5856c4b3a583497e.camel@redhat.com> (raw)
In-Reply-To: <20210504171734.1434054-8-seanjc@google.com>
On Tue, 2021-05-04 at 10:17 -0700, Sean Christopherson wrote:
> Allow userspace to enable RDPID for a guest without also enabling RDTSCP.
> Aside from checking for RDPID support in the obvious flows, VMX also needs
> to set ENABLE_RDTSCP=1 when RDPID is exposed.
>
> For the record, there is no known scenario where enabling RDPID without
> RDTSCP is desirable. But, both AMD and Intel architectures allow for the
> condition, i.e. this is purely to make KVM more architecturally accurate.
>
> Fixes: 41cd02c6f7f6 ("kvm: x86: Expose RDPID in KVM_GET_SUPPORTED_CPUID")
> Cc: stable@vger.kernel.org
> Reported-by: Reiji Watanabe <reijiw@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/svm/svm.c | 6 ++++--
> arch/x86/kvm/vmx/vmx.c | 27 +++++++++++++++++++++++----
> arch/x86/kvm/x86.c | 3 ++-
> 3 files changed, 29 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index b3153d40cc4d..231b9650d864 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -2669,7 +2669,8 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> if (tsc_aux_uret_slot < 0)
> return 1;
> if (!msr_info->host_initiated &&
> - !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
> + !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP) &&
> + !guest_cpuid_has(vcpu, X86_FEATURE_RDPID))
> return 1;
> msr_info->data = svm->tsc_aux;
> break;
> @@ -2891,7 +2892,8 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
> return 1;
>
> if (!msr->host_initiated &&
> - !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
> + !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP) &&
> + !guest_cpuid_has(vcpu, X86_FEATURE_RDPID))
> return 1;
>
> /*
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 990ee339a05f..42e4bbaa299a 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -1788,7 +1788,8 @@ static void setup_msrs(struct vcpu_vmx *vmx)
> if (update_transition_efer(vmx))
> vmx_setup_uret_msr(vmx, MSR_EFER);
>
> - if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDTSCP))
> + if (guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDTSCP) ||
> + guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDPID))
> vmx_setup_uret_msr(vmx, MSR_TSC_AUX);
>
> vmx_setup_uret_msr(vmx, MSR_IA32_TSX_CTRL);
> @@ -1994,7 +1995,8 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> break;
> case MSR_TSC_AUX:
> if (!msr_info->host_initiated &&
> - !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
> + !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP) &&
> + !guest_cpuid_has(vcpu, X86_FEATURE_RDPID))
> return 1;
> goto find_uret_msr;
> case MSR_IA32_DEBUGCTLMSR:
> @@ -2314,7 +2316,8 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> break;
> case MSR_TSC_AUX:
> if (!msr_info->host_initiated &&
> - !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
> + !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP) &&
> + !guest_cpuid_has(vcpu, X86_FEATURE_RDPID))
> return 1;
> /* Check reserved bit, higher 32 bits should be zero */
> if ((data >> 32) != 0)
> @@ -4368,7 +4371,23 @@ static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
> xsaves_enabled, false);
> }
>
> - vmx_adjust_sec_exec_feature(vmx, &exec_control, rdtscp, RDTSCP);
> + /*
> + * RDPID is also gated by ENABLE_RDTSCP, turn on the control if either
> + * feature is exposed to the guest. This creates a virtualization hole
> + * if both are supported in hardware but only one is exposed to the
> + * guest, but letting the guest execute RDTSCP or RDPID when either one
> + * is advertised is preferable to emulating the advertised instruction
> + * in KVM on #UD, and obviously better than incorrectly injecting #UD.
> + */
> + if (cpu_has_vmx_rdtscp()) {
> + bool rdpid_or_rdtscp_enabled =
> + guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP) ||
> + guest_cpuid_has(vcpu, X86_FEATURE_RDPID);
> +
> + vmx_adjust_secondary_exec_control(vmx, &exec_control,
> + SECONDARY_EXEC_ENABLE_RDTSCP,
> + rdpid_or_rdtscp_enabled, false);
> + }
> vmx_adjust_sec_exec_feature(vmx, &exec_control, invpcid, INVPCID);
>
> vmx_adjust_sec_exec_exiting(vmx, &exec_control, rdrand, RDRAND);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index e304447be42d..b4516d303413 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5978,7 +5978,8 @@ static void kvm_init_msr_list(void)
> continue;
> break;
> case MSR_TSC_AUX:
> - if (!kvm_cpu_cap_has(X86_FEATURE_RDTSCP))
> + if (!kvm_cpu_cap_has(X86_FEATURE_RDTSCP) &&
> + !kvm_cpu_cap_has(X86_FEATURE_RDPID))
> continue;
> break;
> case MSR_IA32_UMWAIT_CONTROL:
Reviewed-by : Maxim Levitsky <mlevitsk@redhat.com>
Best regards,
Maxim Levitsky
next prev parent reply other threads:[~2021-05-10 8:20 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-04 17:17 [PATCH 00/15] KVM: x86: RDPID/RDTSCP fixes and uret MSR cleanups Sean Christopherson
2021-05-04 17:17 ` [PATCH 01/15] KVM: VMX: Do not adverise RDPID if ENABLE_RDTSCP control is unsupported Sean Christopherson
2021-05-04 17:37 ` Jim Mattson
2021-05-04 17:53 ` Jim Mattson
2021-05-04 18:14 ` Sean Christopherson
2021-05-05 3:04 ` Reiji Watanabe
2021-05-10 8:03 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 02/15] KVM: x86: Emulate RDPID only if RDTSCP is supported Sean Christopherson
2021-05-04 17:50 ` Jim Mattson
2021-05-05 3:51 ` Reiji Watanabe
2021-05-05 8:01 ` Paolo Bonzini
2021-05-10 8:08 ` Maxim Levitsky
2021-05-10 17:20 ` Sean Christopherson
2021-05-11 12:32 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 03/15] KVM: SVM: Inject #UD on RDTSCP when it should be disabled in the guest Sean Christopherson
2021-05-04 21:45 ` Jim Mattson
2021-05-04 21:53 ` Sean Christopherson
2021-05-04 21:56 ` Jim Mattson
2021-05-04 22:10 ` Sean Christopherson
2021-05-04 22:24 ` Jim Mattson
2021-05-04 21:57 ` Paolo Bonzini
2021-05-04 21:58 ` Jim Mattson
2021-05-10 8:08 ` Maxim Levitsky
2021-05-10 16:56 ` Sean Christopherson
2021-05-11 12:34 ` Maxim Levitsky
2021-05-18 10:59 ` Paolo Bonzini
2021-05-18 19:24 ` Sean Christopherson
2021-05-05 4:26 ` Reiji Watanabe
2021-05-10 8:08 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 04/15] KVM: x86: Move RDPID emulation intercept to its own enum Sean Christopherson
2021-05-04 23:24 ` Jim Mattson
2021-05-10 8:14 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 05/15] KVM: VMX: Disable preemption when probing user return MSRs Sean Christopherson
2021-05-04 23:36 ` Jim Mattson
2021-05-10 8:18 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 06/15] KVM: SVM: Probe and load MSR_TSC_AUX regardless of RDTSCP support in host Sean Christopherson
2021-05-10 8:20 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 07/15] KVM: x86: Add support for RDPID without RDTSCP Sean Christopherson
2021-05-10 8:20 ` Maxim Levitsky [this message]
2021-05-04 17:17 ` [PATCH 08/15] KVM: VMX: Configure list of user return MSRs at module init Sean Christopherson
2021-05-10 8:23 ` Maxim Levitsky
2021-05-10 15:13 ` Sean Christopherson
2021-05-11 12:34 ` Maxim Levitsky
2021-05-11 20:10 ` Sean Christopherson
2021-05-04 17:17 ` [PATCH 09/15] KVM: VMX: Use flag to indicate "active" uret MSRs instead of sorting list Sean Christopherson
2021-05-08 3:31 ` Reiji Watanabe
2021-05-10 16:43 ` Sean Christopherson
2021-05-10 17:55 ` Reiji Watanabe
2021-05-10 8:25 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 10/15] KVM: VMX: Use common x86's uret MSR list as the one true list Sean Christopherson
2021-05-10 8:25 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 11/15] KVM: VMX: Disable loading of TSX_CTRL MSR the more conventional way Sean Christopherson
2021-05-05 8:49 ` Paolo Bonzini
2021-05-05 15:36 ` Sean Christopherson
2021-05-05 15:50 ` Paolo Bonzini
2021-05-10 8:26 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 12/15] KVM: x86: Export the number of uret MSRs to vendor modules Sean Christopherson
2021-05-10 8:27 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 13/15] KVM: x86: Move uret MSR slot management to common x86 Sean Christopherson
2021-05-10 8:28 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 14/15] KVM: x86: Tie Intel and AMD behavior for MSR_TSC_AUX to guest CPU model Sean Christopherson
2021-05-10 8:29 ` Maxim Levitsky
2021-05-10 16:50 ` Sean Christopherson
2021-05-10 17:11 ` Jim Mattson
2021-05-11 12:34 ` Maxim Levitsky
2021-05-04 17:17 ` [PATCH 15/15] KVM: x86: Hide RDTSCP and RDPID if MSR_TSC_AUX probing failed Sean Christopherson
2021-05-10 8:29 ` Maxim Levitsky
2021-05-05 8:51 ` [PATCH 00/15] KVM: x86: RDPID/RDTSCP fixes and uret MSR cleanups Paolo Bonzini
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