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From: Andy Lutomirski <luto@kernel.org>
To: Sean Christopherson <seanjc@google.com>
Cc: Wei Huang <wei.huang2@amd.com>, kvm list <kvm@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Joerg Roedel <joro@8bytes.org>, Borislav Petkov <bp@alien8.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, X86 ML <x86@kernel.org>,
	Jim Mattson <jmattson@google.com>,
	Wanpeng Li <wanpengli@tencent.com>, Bandan Das <bsd@redhat.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Maxim Levitsky <mlevitsk@redhat.com>
Subject: Re: [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions
Date: Tue, 12 Jan 2021 10:58:29 -0800	[thread overview]
Message-ID: <CALCETrXsNBmXg8C4Tmz4YgTSAykKoWFHgXHFFcK-C65LUQ0r4w@mail.gmail.com> (raw)
In-Reply-To: <X/3jap249oBJ/a6s@google.com>

On Tue, Jan 12, 2021 at 9:59 AM Sean Christopherson <seanjc@google.com> wrote:
>
> On Tue, Jan 12, 2021, Sean Christopherson wrote:
> > On Tue, Jan 12, 2021, Wei Huang wrote:
> > > From: Bandan Das <bsd@redhat.com>
> > >
> > > While running VM related instructions (VMRUN/VMSAVE/VMLOAD), some AMD
> > > CPUs check EAX against reserved memory regions (e.g. SMM memory on host)
> > > before checking VMCB's instruction intercept.
> >
> > It would be very helpful to list exactly which CPUs are/aren't affected, even if
> > that just means stating something like "all CPUs before XYZ".  Given patch 2/2,
> > I assume it's all CPUs without the new CPUID flag?
>
> Ah, despite calling this an 'errata', the bad behavior is explicitly documented
> in the APM, i.e. it's an architecture bug, not a silicon bug.
>
> Can you reword the changelog to make it clear that the premature #GP is the
> correct architectural behavior for CPUs without the new CPUID flag?

Andrew Cooper points out that there may be a nicer workaround.  Make
sure that the SMRAM and HT region (FFFD00000000 - FFFFFFFFFFFF) are
marked as reserved in the guest, too.

--Andy

  reply	other threads:[~2021-01-12 18:59 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-12  6:37 [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions Wei Huang
2021-01-12  6:37 ` [PATCH 2/2] KVM: SVM: Add support for VMCB address check change Wei Huang
2021-01-12 19:18   ` Sean Christopherson
2021-01-14 11:39     ` Maxim Levitsky
2021-01-14 12:04   ` Maxim Levitsky
2021-01-12 11:09 ` [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions Maxim Levitsky
2021-01-12 21:05   ` Wei Huang
2021-01-12 12:15 ` Vitaly Kuznetsov
2021-01-12 15:11   ` Andy Lutomirski
2021-01-12 15:17     ` Maxim Levitsky
2021-01-12 15:22       ` Andy Lutomirski
2021-01-12 15:46         ` Bandan Das
2021-01-12 15:51           ` Andy Lutomirski
2021-01-12 17:56             ` Sean Christopherson
2021-01-13  4:55               ` Wei Huang
2021-01-12 21:50   ` Wei Huang
2021-01-12 14:01 ` Paolo Bonzini
2021-01-12 17:42   ` Sean Christopherson
2021-01-13 12:35     ` Paolo Bonzini
2021-01-15  7:00   ` Wei Huang
2021-01-17 18:20     ` Paolo Bonzini
2021-01-12 17:36 ` Sean Christopherson
2021-01-12 17:59   ` Sean Christopherson
2021-01-12 18:58     ` Andy Lutomirski [this message]
2021-01-13  5:15       ` Wei Huang
2021-01-14 11:42         ` Maxim Levitsky
2021-01-13  5:03     ` Wei Huang
2021-01-13 12:40     ` Paolo Bonzini
2021-01-12 19:40 ` Sean Christopherson
2021-01-12 20:00   ` Bandan Das
2021-01-14 11:47     ` Maxim Levitsky
2021-01-14 17:19       ` Sean Christopherson
2021-01-14 11:55 ` Maxim Levitsky

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