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From: Chao Gao <chao.gao@intel.com>
To: Xiaoyao Li <xiaoyao.li@intel.com>
Cc: <kvm@vger.kernel.org>, Jiaan Lu <jiaan.lu@intel.com>,
	Zhang Chen <chen.zhang@intel.com>,
	Sean Christopherson <seanjc@google.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>, <x86@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v2 02/11] KVM: x86: Advertise CPUID.7.2.EDX and RRSBA_CTRL support
Date: Tue, 16 May 2023 11:01:38 +0800	[thread overview]
Message-ID: <ZGLyEhKH+MoCY/R4@chao-email> (raw)
In-Reply-To: <9c75663c-6363-34e7-8341-d8f719365768@intel.com>

On Tue, May 16, 2023 at 10:22:22AM +0800, Xiaoyao Li wrote:
>> > I think we need to fix this bug at first.
>> 
>> I have no idea how to fix the "bug" without intercepting the MSR. The
>> performance penalty makes me think intercepting the MSR is not a viable
>> solution.
>
>I thought correctness always takes higher priority over performance.

It is generally true. however, there are situations where we should make
trade-offs between correctness and other factors (like performance):

E.g., instructions without control bits, to be 100% compliant with CPU
spec, in theory, VMMs can trap/decode every instruction and inject #UD
if a guest tries to use some instructions it shouldn't.

  reply	other threads:[~2023-05-16  3:02 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-14  6:25 [RFC PATCH v2 00/11] Intel IA32_SPEC_CTRL Virtualization Chao Gao
2023-04-14  6:25 ` [RFC PATCH v2 01/11] x86/msr-index: Add bit definitions for BHI_DIS_S and BHI_NO Chao Gao
2023-04-14  9:52   ` Binbin Wu
2023-04-14  6:25 ` [RFC PATCH v2 02/11] KVM: x86: Advertise CPUID.7.2.EDX and RRSBA_CTRL support Chao Gao
2023-04-16  7:04   ` Binbin Wu
2023-04-16 13:25     ` Chao Gao
2023-05-15  6:53   ` Xiaoyao Li
2023-05-16  2:04     ` Chao Gao
2023-05-16  2:22       ` Xiaoyao Li
2023-05-16  3:01         ` Chao Gao [this message]
2023-05-16  7:03           ` Xiaoyao Li
2023-05-16  9:09             ` Chao Gao
2023-05-18  9:50               ` Xiaoyao Li
2023-05-19  9:43                 ` Chao Gao
2023-04-14  6:25 ` [RFC PATCH v2 03/11] KVM: x86: Advertise BHI_CTRL support Chao Gao
2023-05-15  7:14   ` Xiaoyao Li
2023-04-14  6:25 ` [RFC PATCH v2 04/11] KVM: VMX: Add IA32_SPEC_CTRL virtualization support Chao Gao
2023-04-17  3:17   ` Binbin Wu
2023-04-18  2:07     ` Chao Gao
2023-04-17  6:48   ` Chenyi Qiang
2023-04-17  7:31     ` Chao Gao
2023-05-16  7:16   ` Xiaoyao Li
2023-05-16  9:20     ` Chao Gao
2023-04-14  6:25 ` [RFC PATCH v2 05/11] x86/bugs: Use Virtual MSRs to request hardware mitigations Chao Gao
2023-04-17 13:43   ` Binbin Wu
2023-04-18  2:01     ` Chao Gao
2023-04-14  6:25 ` [RFC PATCH v2 06/11] KVM: x86: Advertise ARCH_CAP_VIRTUAL_ENUM support Chao Gao
2023-05-18 10:14   ` Xiaoyao Li
2023-05-19  9:57     ` Chao Gao
2023-05-22  1:02       ` Xiaoyao Li
2023-04-14  6:25 ` [RFC PATCH v2 07/11] KVM: VMX: Advertise MITIGATION_CTRL support Chao Gao
2023-04-14  6:25 ` [RFC PATCH v2 08/11] KVM: VMX: Advertise MITI_ENUM_RETPOLINE_S_SUPPORT Chao Gao
2023-05-18 10:25   ` Xiaoyao Li
2023-05-19 10:26     ` Chao Gao
2023-05-22  9:43   ` Liu, Jingqi
2023-04-14  6:25 ` [RFC PATCH v2 09/11] KVM: VMX: Advertise MITI_CTRL_BHB_CLEAR_SEQ_S_SUPPORT Chao Gao
2023-05-22  9:41   ` Liu, Jingqi
2023-04-14  6:25 ` [RFC PATCH v2 10/11] KVM: selftests: Add tests for virtual enumeration/mitigation MSRs Chao Gao
2023-05-22  9:39   ` Liu, Jingqi
2023-04-14  6:25 ` [RFC PATCH v2 11/11] KVM: selftests: Add tests for IA32_SPEC_CTRL MSR Chao Gao
2023-04-14  9:51 ` [RFC PATCH v2 00/11] Intel IA32_SPEC_CTRL Virtualization Binbin Wu
2023-04-14 22:10   ` Pawan Gupta

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