From: Paolo Bonzini <pbonzini@redhat.com>
To: Xiaoyao Li <xiaoyao.li@intel.com>,
Like Xu <like.xu.linux@gmail.com>,
Jun Nakajima <jun.nakajima@intel.com>
Cc: Sean Christopherson <seanjc@google.com>,
Jim Mattson <jmattson@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [DROP][PATCH] KVM: x86: Fix the #GP(0) and #UD conditions for XSETBV emulation
Date: Thu, 20 Jan 2022 10:49:00 +0100 [thread overview]
Message-ID: <5de5120f-e4b1-5888-58cb-b642361ea5cd@redhat.com> (raw)
In-Reply-To: <d0855fb0-4e98-1090-a230-132b08864ed3@intel.com>
On 1/20/22 10:31, Xiaoyao Li wrote:
>>
>> So while my gut feeling that #UD would not cause a vmexit was correct,
>> technically I was reading the SDM incorrectly.
>
> SDM also states
>
> Certain exceptions have priority over VM exits. These include
> invalid-opcode exception, faults based on privilege level,
> and general-protection exceptions that are based on checking
> I/O permission bits in the task-state segment(TSS)
>
> in "Relative Priority of Faults and VM Exits"
>
> So my understanding is that the architectural check always takes the
> higher priority than VM exit.
Good point! It's right above in 25.1.1. I was confused by the specific
mention of GETSEC, but the reason for the footnote is because undefined
GETSEC leaves cause a vmexit instead of #UD, and GETSEC vmexits also
override #GP faults based on privilege level.
Thanks,
Paolo
prev parent reply other threads:[~2022-01-20 9:49 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-17 7:24 [PATCH] KVM: x86: Fix the #GP(0) and #UD conditions for XSETBV emulation Like Xu
2022-01-17 8:31 ` Paolo Bonzini
2022-01-17 9:44 ` Like Xu
2022-01-17 11:18 ` Paolo Bonzini
2022-01-20 7:48 ` [DROP][PATCH] " Like Xu
2022-01-20 9:17 ` Paolo Bonzini
2022-01-20 9:31 ` Xiaoyao Li
2022-01-20 9:49 ` Paolo Bonzini [this message]
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