From: Thomas Gleixner <tglx@linutronix.de>
To: Jim Mattson <jmattson@google.com>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Jim Mattson <jmattson@google.com>,
Sandipan Das <sandipan.das@amd.com>,
Kai Huang <kai.huang@intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org
Subject: Re: [PATCH v3 0/4] Distinguish between variants of IBPB
Date: Sun, 25 Aug 2024 14:17:04 +0200 [thread overview]
Message-ID: <875xrog5kv.ffs@tglx> (raw)
In-Reply-To: <20240823185323.2563194-1-jmattson@google.com>
On Fri, Aug 23 2024 at 11:53, Jim Mattson wrote:
> Prior to Zen4, AMD's IBPB did not flush the RAS (or, in Intel
> terminology, the RSB). Hence, the older version of AMD's IBPB was not
> equivalent to Intel's IBPB. However, KVM has been treating them as
> equivalent, synthesizing Intel's CPUID.(EAX=7,ECX=0):EDX[bit 26] on any
> platform that supports the synthetic features X86_FEATURE_IBPB and
> X86_FEATURE_IBRS.
>
> Equivalence also requires a previously ignored feature on the AMD side,
> CPUID Fn8000_0008_EBX[IBPB_RET], which is enumerated on Zen4.
>
> v3: Pass through IBPB_RET from hardware to userspace. [Tom]
> Derive AMD_IBPB from X86_FEATURE_SPEC_CTRL rather than
> X86_FEATURE_IBPB. [Tom]
> Clarify semantics of X86_FEATURE_IBPB.
>
> v2: Use IBPB_RET to identify semantic equality. [Venkatesh]
Assuming this goes through the KVM tree:
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
prev parent reply other threads:[~2024-08-25 12:17 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-23 18:53 [PATCH v3 0/4] Distinguish between variants of IBPB Jim Mattson
2024-08-23 18:53 ` [PATCH v3 1/4] x86/cpufeatures: Clarify semantics of X86_FEATURE_IBPB Jim Mattson
2024-08-26 20:33 ` Pawan Gupta
2024-08-26 20:59 ` Jim Mattson
2024-08-26 22:28 ` Pawan Gupta
2024-08-23 18:53 ` [PATCH v3 2/4] x86/cpufeatures: Define X86_FEATURE_AMD_IBPB_RET Jim Mattson
2024-08-23 18:53 ` [PATCH v3 3/4] KVM: x86: Advertise AMD_IBPB_RET to userspace Jim Mattson
2024-08-23 18:53 ` [PATCH v3 4/4] KVM: x86: AMD's IBPB is not equivalent to Intel's IBPB Jim Mattson
2024-08-23 19:40 ` Tom Lendacky
2024-08-23 20:51 ` Sean Christopherson
2024-08-23 22:00 ` Jim Mattson
2024-08-23 22:12 ` Tom Lendacky
2024-08-23 22:48 ` Jim Mattson
2024-08-23 23:49 ` Jim Mattson
2024-08-29 0:21 ` Sean Christopherson
2024-08-23 19:41 ` [PATCH v3 0/4] Distinguish between variants of IBPB Tom Lendacky
2024-08-25 12:17 ` Thomas Gleixner [this message]
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