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 11/15] KVM: VMX: Disable loading of TSX_CTRL MSR the more conventional way
Date: Mon, 10 May 2021 11:26:31 +0300 [thread overview]
Message-ID: <a8595d87b67616a7ac25784c6acdebbd170d2f5a.camel@redhat.com> (raw)
In-Reply-To: <20210504171734.1434054-12-seanjc@google.com>
On Tue, 2021-05-04 at 10:17 -0700, Sean Christopherson wrote:
> Tag TSX_CTRL as not needing to be loaded when RTM isn't supported in the
> host. Crushing the write mask to '0' has the same effect, but requires
> more mental gymnastics to understand.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/vmx/vmx.c | 22 ++++++++++------------
> 1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 4b432d2bbd06..7a53568b34fc 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -1771,7 +1771,13 @@ static void setup_msrs(struct vcpu_vmx *vmx)
> guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDTSCP) ||
> guest_cpuid_has(&vmx->vcpu, X86_FEATURE_RDPID));
>
> - vmx_setup_uret_msr(vmx, MSR_IA32_TSX_CTRL, true);
> + /*
> + * hle=0, rtm=0, tsx_ctrl=1 can be found with some combinations of new
> + * kernel and old userspace. If those guests run on a tsx=off host, do
> + * allow guests to use TSX_CTRL, but don't change the value in hardware
> + * so that TSX remains always disabled.
> + */
> + vmx_setup_uret_msr(vmx, MSR_IA32_TSX_CTRL, boot_cpu_has(X86_FEATURE_RTM));
>
> if (cpu_has_vmx_msr_bitmap())
> vmx_update_msr_bitmap(&vmx->vcpu);
> @@ -6919,23 +6925,15 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
> vmx->guest_uret_msrs[i].data = 0;
> vmx->guest_uret_msrs[i].mask = -1ull;
> }
> - tsx_ctrl = vmx_find_uret_msr(vmx, MSR_IA32_TSX_CTRL);
> - if (tsx_ctrl) {
> + if (boot_cpu_has(X86_FEATURE_RTM)) {
> /*
> * TSX_CTRL_CPUID_CLEAR is handled in the CPUID interception.
> * Keep the host value unchanged to avoid changing CPUID bits
> * under the host kernel's feet.
> - *
> - * hle=0, rtm=0, tsx_ctrl=1 can be found with some combinations
> - * of new kernel and old userspace. If those guests run on a
> - * tsx=off host, do allow guests to use TSX_CTRL, but do not
> - * change the value on the host so that TSX remains always
> - * disabled.
> */
> - if (boot_cpu_has(X86_FEATURE_RTM))
> + tsx_ctrl = vmx_find_uret_msr(vmx, MSR_IA32_TSX_CTRL);
> + if (tsx_ctrl)
> vmx->guest_uret_msrs[i].mask = ~(u64)TSX_CTRL_CPUID_CLEAR;
> - else
> - vmx->guest_uret_msrs[i].mask = 0;
> }
>
> err = alloc_loaded_vmcs(&vmx->vmcs01);
I also agree that commit message should be updated as Paolo said,
but other than that:
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Best regards,
Maxim Levitsky <mlevitsk@redhat.com>
next prev parent reply other threads:[~2021-05-10 8:26 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
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 [this message]
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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