From: Borislav Petkov <bp@alien8.de>
To: Jim Mattson <jmattson@google.com>,
Sean Christopherson <seanjc@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH v2 0/3] KVM: EFER.LMSLE cleanup
Date: Wed, 21 Sep 2022 11:28:24 +0200 [thread overview]
Message-ID: <YyrZOLq8z+lIORvP@zn.tnic> (raw)
In-Reply-To: <CALMp9eQijCKS-E_OWJkxdqAur3BthciOWEtEPH5YKd0-HJiQQA@mail.gmail.com>
On Tue, Sep 20, 2022 at 09:36:18PM +0000, Sean Christopherson wrote:
> Yes, but ideally KVM would explicitly tell the guest "you don't have LMSLE".
> Probably a moot point, but at the same time I don't see a reason not to be
> explicit.
Yes but...
On Tue, Sep 20, 2022 at 02:36:34PM -0700, Jim Mattson wrote:
> Reporting that CPUID bit gives us the right to raise #GP. AMD CPUs
> (going way back) that don't report EferLmsleUnsupported do not raise
> #GP.
... what does "gives us the right" mean exactly?
I'm pretty sure I'm missing something about how KVM works but wouldn't
it raise a guest #GP when the guest tries to set an unsupported EFER
bit? I.e., why do you need to explicitly do
kvm_cpu_cap_set(X86_FEATURE_NO_LMSLE);
and not handle this like any other EFER reserved bit?
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-09-21 9:28 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-20 20:59 [PATCH v2 0/3] KVM: EFER.LMSLE cleanup Jim Mattson
2022-09-20 20:59 ` [PATCH v2 1/3] Revert "KVM: SVM: Allow EFER.LMSLE to be set with nested svm" Jim Mattson
2022-09-20 20:59 ` [PATCH v2 2/3] x86/cpufeatures: Introduce X86_FEATURE_NO_LMSLE Jim Mattson
2022-09-21 16:07 ` Borislav Petkov
2022-09-20 20:59 ` [PATCH v2 3/3] KVM: SVM: Unconditionally enumerate EferLmsleUnsupported Jim Mattson
2022-10-07 22:41 ` Sean Christopherson
2022-09-20 21:17 ` [PATCH v2 0/3] KVM: EFER.LMSLE cleanup Borislav Petkov
2022-09-20 21:36 ` Sean Christopherson
2022-09-20 21:36 ` Jim Mattson
2022-09-21 9:28 ` Borislav Petkov [this message]
2022-09-21 13:45 ` Jim Mattson
2022-09-21 13:54 ` Borislav Petkov
2022-09-21 15:11 ` Jim Mattson
2022-09-21 16:06 ` Borislav Petkov
2022-09-21 16:23 ` Jim Mattson
2022-09-21 17:11 ` Borislav Petkov
2022-09-21 17:45 ` Jim Mattson
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