From: Jim Mattson <jmattson@google.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Sean Christopherson <seanjc@google.com>,
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 09:23:40 -0700 [thread overview]
Message-ID: <CALMp9eQ-qkjBm8qPhOaMzZLWeHJcrwksV+XLQ9DfOQ_i1aykqQ@mail.gmail.com> (raw)
In-Reply-To: <Yys2ikzV73upzlEj@zn.tnic>
On Wed, Sep 21, 2022 at 9:06 AM Borislav Petkov <bp@alien8.de> wrote:
>
> On Wed, Sep 21, 2022 at 08:11:29AM -0700, Jim Mattson wrote:
> > Yes, after the revert, KVM will treat the bit as reserved, and it will
> > synthesize a #GP, *in violation of the architectural specification.*
>
> Architectural, schmarchitectural... Intel hasn't implemented it so meh.
>
> > KVM can't just decide willy nilly to reserve arbitrary bits. If it is
> > in violation of AMD's architectural specification, the virtual CPU is
> > defective.
>
> Grrr, after your revert that this bit was *only* reserved and nothing
> else to KVM. Like every other reserved bit in EFER. Yeah, yeah, AMD
> specified it as architectural but Intel didn't implement it so there's
> this thing on paper and there's reality...
AMD defined the 64-bit x86 extensions while Intel was distracted with
their VLIW science fair project. In this space, Intel produces AMD64
compatible CPUs. The definitive specification comes from AMD (which is
sad, because AMD's documentation is abysmal).
next prev parent reply other threads:[~2022-09-21 16:38 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
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 [this message]
2022-09-21 17:11 ` Borislav Petkov
2022-09-21 17:45 ` Jim Mattson
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