From: Paolo Bonzini <pbonzini@redhat.com>
To: Emanuele Giuseppe Esposito <eesposit@redhat.com>, kvm@vger.kernel.org
Cc: Maxim Levitsky <mlevitsk@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 2/7] nSVM: introduce smv->nested.save to cache save area fields
Date: Thu, 11 Nov 2021 14:52:31 +0100 [thread overview]
Message-ID: <49852dbc-548d-5bf1-6254-ec69d3041961@redhat.com> (raw)
In-Reply-To: <20211103140527.752797-3-eesposit@redhat.com>
On 11/3/21 15:05, Emanuele Giuseppe Esposito wrote:
> Note that in svm_set_nested_state() we want to cache the L2
> save state only if we are in normal non guest mode, because
> otherwise it is not touched.
I think that call to nested_copy_vmcb_save_to_cache is not necessary at
all, because svm->nested.save is not used afterwards and is not valid
after VMRUN.
The relevant checks have already been done before:
if (!(vcpu->arch.efer & EFER_SVME)) {
/* GIF=1 and no guest mode are required if SVME=0. */
if (kvm_state->flags != KVM_STATE_NESTED_GIF_SET)
return -EINVAL;
}
...
/*
* Processor state contains L2 state. Check that it is
* valid for guest mode (see nested_vmcb_check_save).
*/
cr0 = kvm_read_cr0(vcpu);
if (((cr0 & X86_CR0_CD) == 0) && (cr0 & X86_CR0_NW))
goto out_free;
(and all other checks are done by KVM_SET_SREGS, KVM_SET_DEBUGREGS etc.)
Paolo
next prev parent reply other threads:[~2021-11-11 13:52 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-03 14:05 [PATCH v5 0/7] KVM: nSVM: avoid TOC/TOU race when checking vmcb12 Emanuele Giuseppe Esposito
2021-11-03 14:05 ` [PATCH v5 1/7] KVM: nSVM: move nested_vmcb_check_cr3_cr4 logic in nested_vmcb_valid_sregs Emanuele Giuseppe Esposito
2021-11-03 14:05 ` [PATCH v5 2/7] nSVM: introduce smv->nested.save to cache save area fields Emanuele Giuseppe Esposito
2021-11-03 17:02 ` Maxim Levitsky
2021-11-11 13:52 ` Paolo Bonzini [this message]
2021-11-12 7:43 ` Maxim Levitsky
2021-11-03 14:05 ` [PATCH v5 3/7] nSVM: rename nested_load_control_from_vmcb12 in nested_copy_vmcb_control_to_cache Emanuele Giuseppe Esposito
2021-11-03 17:03 ` Maxim Levitsky
2021-11-03 14:05 ` [PATCH v5 4/7] nSVM: use vmcb_save_area_cached in nested_vmcb_valid_sregs() Emanuele Giuseppe Esposito
2021-11-03 17:03 ` Maxim Levitsky
2021-11-03 14:05 ` [PATCH v5 5/7] nSVM: use svm->nested.save to load vmcb12 registers and avoid TOC/TOU races Emanuele Giuseppe Esposito
2021-11-03 14:05 ` [PATCH v5 6/7] nSVM: introduce struct vmcb_ctrl_area_cached Emanuele Giuseppe Esposito
2021-11-03 14:05 ` [PATCH v5 7/7] nSVM: use vmcb_ctrl_area_cached instead of vmcb_control_area in struct svm_nested_state Emanuele Giuseppe Esposito
2021-11-03 17:05 ` Maxim Levitsky
2021-11-11 13:55 ` [PATCH v5 0/7] KVM: nSVM: avoid TOC/TOU race when checking vmcb12 Paolo Bonzini
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