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From: Sean Christopherson <seanjc@google.com>
To: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	Borislav Petkov <bp@alien8.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Babu Moger <babu.moger@amd.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	David.Kaplan@amd.com, Andrew Cooper <andrew.cooper3@citrix.com>,
	Nikolay Borisov <nik.borisov@suse.com>,
	gregkh@linuxfoundation.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 05/23] KVM: x86: Add SBPB support
Date: Fri, 25 Aug 2023 11:20:18 -0700	[thread overview]
Message-ID: <ZOjw4uPOKltexXOp@google.com> (raw)
In-Reply-To: <a4ab1e7fe50096d50fde33e739ed2da40b41ea6a.1692919072.git.jpoimboe@kernel.org>

On Fri, Aug 25, 2023, Josh Poimboeuf wrote:
> Add support for the AMD Selective Branch Predictor Barrier (SBPB) by
> advertising the CPUID bit and handling PRED_CMD writes accordingly.

Same as the other patch, please call out that not doing the "standard" F(SBPB)
is intentional, e.g.

  Note, like SRSO_NO and IBPB_BRTYPE before it, advertise support for SBPB
  even if it's not enumerated by in the raw CPUID.  Some CPUs that gained
  support via a uCode patch don't report SBPB via CPUID (the kernel forces
  the flag).

And again, feel free to take this through tip if this should go in 6.6.  Turns out
our Milan systems have the SBPB fun, so I was able to actually test this, including
the emulated WRMSR handling (KVM allows forcing emulation via a magic prefix).  I
have a KVM-Unit-Test patch that I'll post next week.

Thanks Josh!

Acked-by: Sean Christopherson <seanjc@google.com>

> Co-developed-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

  reply	other threads:[~2023-08-25 18:21 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-25  7:01 [PATCH v2 00/23] SRSO fixes/cleanups Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 01/23] x86/srso: Fix srso_show_state() side effect Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 02/23] x86/srso: Set CPUID feature bits independently of bug or mitigation status Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 03/23] x86/srso: Don't probe microcode in a guest Josh Poimboeuf
2023-08-25  7:52   ` Andrew Cooper
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 04/23] KVM: x86: Add IBPB_BRTYPE support Josh Poimboeuf
2023-08-25 18:15   ` Sean Christopherson
2023-08-26 15:49     ` Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 05/23] KVM: x86: Add SBPB support Josh Poimboeuf
2023-08-25 18:20   ` Sean Christopherson [this message]
2023-08-25  7:01 ` [PATCH 06/23] x86/srso: Fix SBPB enablement for spec_rstack_overflow=off Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 07/23] x86/srso: Fix SBPB enablement for (possible) future fixed HW Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 08/23] x86/srso: Print actual mitigation if requested mitigation isn't possible Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 09/23] x86/srso: Print mitigation for retbleed IBPB case Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 10/23] x86/srso: Fix vulnerability reporting for missing microcode Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-09-01  9:40     ` Borislav Petkov
2023-09-02 10:46       ` Ingo Molnar
2023-09-02 17:04         ` Borislav Petkov
2023-09-03 14:37           ` Borislav Petkov
2023-09-05  4:57         ` Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 11/23] x86/srso: Fix unret validation dependencies Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 12/23] x86/alternatives: Remove faulty optimization Josh Poimboeuf
2023-08-25  9:20   ` Ingo Molnar
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25 10:27   ` [tip: x86/urgent] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 13/23] x86/srso: Improve i-cache locality for alias mitigation Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 14/23] x86/srso: Unexport untraining functions Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 15/23] x86/srso: Remove 'pred_cmd' label Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25 19:51   ` [PATCH 15/23] " Nikolay Borisov
2023-08-26 15:45     ` Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 16/23] x86/bugs: Remove default case for fully switched enums Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-09-02  9:02   ` [PATCH 16/23] " Borislav Petkov
2023-09-05  5:08     ` Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 17/23] x86/srso: Move retbleed IBPB check into existing 'has_microcode' code block Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 18/23] x86/srso: Remove redundant X86_FEATURE_ENTRY_IBPB check Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-09-02  9:10   ` [PATCH 18/23] " Borislav Petkov
2023-08-25  7:01 ` [PATCH 19/23] x86/srso: Disentangle rethunk-dependent options Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 20/23] x86/rethunk: Use SYM_CODE_START[_LOCAL]_NOALIGN macros Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 21/23] x86/retpoline: Remove .text..__x86.return_thunk section Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 22/23] x86/nospec: Refactor UNTRAIN_RET[_*] Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25 18:22   ` [PATCH 22/23] " Nikolay Borisov
2023-08-26 15:42     ` Josh Poimboeuf
2023-08-25  7:01 ` [PATCH 23/23] x86/calldepth: Rename __x86_return_skl() to call_depth_return_thunk() Josh Poimboeuf
2023-08-25 10:19   ` [tip: x86/bugs] " tip-bot2 for Josh Poimboeuf
2023-08-25 10:38 ` [PATCH v2 00/23] SRSO fixes/cleanups Ingo Molnar
2023-08-26 15:57   ` Josh Poimboeuf
2023-08-26 17:00     ` Ingo Molnar
2023-10-05  1:29 ` Sean Christopherson

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