From: Yang Weijiang <weijiang.yang@intel.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
Yang Weijiang <weijiang.yang@intel.com>,
pbonzini@redhat.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] KVM: nVMX: Sync L2 guest CET states between L1/L2
Date: Wed, 3 Mar 2021 14:09:39 +0800 [thread overview]
Message-ID: <20210303060939.GA8243@local-michael-cet-test.sh.intel.com> (raw)
In-Reply-To: <87y2f5etc2.fsf@vitty.brq.redhat.com>
On Tue, Mar 02, 2021 at 11:35:41AM +0100, Vitaly Kuznetsov wrote:
> Sean Christopherson <seanjc@google.com> writes:
>
> > +Vitaly
> >
> > On Thu, Feb 25, 2021, Yang Weijiang wrote:
> >> These fields are rarely updated by L1 QEMU/KVM, sync them when L1 is trying to
> >> read/write them and after they're changed. If CET guest entry-load bit is not
> >> set by L1 guest, migrate them to L2 manaully.
> >>
> >> Suggested-by: Sean Christopherson <seanjc@google.com>
> >> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> >>
> >> change in v2:
> >> - Per Sean's review feedback, change CET guest states as rarely-updated fields.
> >> And also migrate L1's CET states to L2 if the entry-load bit is not set.
> >> - Opportunistically removed one blank line.
> >> ---
> >> arch/x86/kvm/cpuid.c | 1 -
> >> arch/x86/kvm/vmx/nested.c | 29 +++++++++++++++++++++++++++++
> >> arch/x86/kvm/vmx/vmx.h | 3 +++
> >> 3 files changed, 32 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> >> index 46087bca9418..afc97122c05c 100644
> >> --- a/arch/x86/kvm/cpuid.c
> >> +++ b/arch/x86/kvm/cpuid.c
> >> @@ -143,7 +143,6 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
> >> }
> >> vcpu->arch.guest_supported_xss =
> >> (((u64)best->edx << 32) | best->ecx) & supported_xss;
> >> -
> >> } else {
> >> vcpu->arch.guest_supported_xss = 0;
> >> }
> >> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> >> index 9728efd529a1..1703b8874fad 100644
> >> --- a/arch/x86/kvm/vmx/nested.c
> >> +++ b/arch/x86/kvm/vmx/nested.c
> >> @@ -2516,6 +2516,12 @@ static void prepare_vmcs02_rare(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
> >> vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.guest.nr);
> >>
> >> set_cr4_guest_host_mask(vmx);
> >> +
> >> + if (kvm_cet_supported()) {
> >
> > This needs to be conditioned on CET coming from vmcs12, it's on the loading of
> > host state on VM-Exit that is unconditional (if CET is supported).
> >
> > if (kvm_cet_supported() && vmx->nested.nested_run_pending &&
> > (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_CET_STATE)) {
> >
> > I also assume these should be guarded by one of the eVMCS fields, though a quick
> > search of the public docs didn't provide a hit on the CET fields.
> >
> > Vitaly, any idea if these will be GUEST_GRP2 or something else?
> >
>
> The latest published TLFS I see is 6.0b and it doesn't list anything CET
> related in eVMCS v1.0 :-( So I agree with Paolo: we just need to adjust
> EVMCS1_UNSUPPORTED_VMENTRY_CTRL/ EVMCS1_UNSUPPORTED_VMEXIT_CTRL for now
> and enable it separately later.
>
Thanks Vitaly and Paolo.
New patches have been sent to community.
> >> + vmcs_writel(GUEST_SSP, vmcs12->guest_ssp);
> >> + vmcs_writel(GUEST_S_CET, vmcs12->guest_s_cet);
> >> + vmcs_writel(GUEST_INTR_SSP_TABLE, vmcs12->guest_ssp_tbl);
> >> + }
> >> }
> >
>
> --
> Vitaly
next prev parent reply other threads:[~2021-03-03 12:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-25 3:09 [PATCH] KVM: nVMX: Set X86_CR4_CET in cr4_fixed1_bits if CET IBT is enabled Yang Weijiang
2021-02-25 3:09 ` [PATCH v2] KVM: nVMX: Sync L2 guest CET states between L1/L2 Yang Weijiang
2021-03-01 17:46 ` Sean Christopherson
2021-03-02 9:05 ` Yang Weijiang
2021-03-02 9:33 ` Paolo Bonzini
2021-03-02 10:35 ` Vitaly Kuznetsov
2021-03-03 6:09 ` Yang Weijiang [this message]
2021-03-01 17:39 ` [PATCH] KVM: nVMX: Set X86_CR4_CET in cr4_fixed1_bits if CET IBT is enabled Sean Christopherson
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