From: Sean Christopherson <seanjc@google.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Brendan Jackman <jackmanb@google.com>
Subject: Re: [PATCH v4 1/8] x86/bugs: Use VM_CLEAR_CPU_BUFFERS in VMX as well
Date: Tue, 11 Nov 2025 14:03:40 -0800 [thread overview]
Message-ID: <aROyvB0kZSQYmCh0@google.com> (raw)
In-Reply-To: <20251107190534.GTaQ5C_l_UsZmQR1ph@fat_crate.local>
On Fri, Nov 07, 2025, Borislav Petkov wrote:
> On Mon, Nov 03, 2025 at 10:18:40AM -0800, Pawan Gupta wrote:
> > diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
> > index 08ed5a2e46a5..2be9be782013 100644
> > --- a/arch/x86/include/asm/nospec-branch.h
> > +++ b/arch/x86/include/asm/nospec-branch.h
> > @@ -321,9 +321,11 @@
> > #endif
> > .endm
> >
> > +/* Primarily used in exit-to-userspace path */
>
> What does "primarily" mean here?
>
> $ git grep -w CLEAR_CPU_BUFFERS
>
> says *only* the kernel->user vector.
How about:
/* If necessary, emit VERW on exit-to-userspace to clear CPU buffers. */
#define CLEAR_CPU_BUFFERS \
ALTERNATIVE "", __CLEAR_CPU_BUFFERS, X86_FEATURE_CLEAR_CPU_BUF
>
> > #define CLEAR_CPU_BUFFERS \
> > __CLEAR_CPU_BUFFERS X86_FEATURE_CLEAR_CPU_BUF
> >
> > +/* For use in KVM */
>
> That's why the "VM_" prefix is there.
Ya, and this goes away (moved into SVM) by the end of the series.
next prev parent reply other threads:[~2025-11-11 22:03 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-31 0:30 [PATCH v4 0/8] x86/bugs: KVM: L1TF and MMIO Stale Data cleanups Sean Christopherson
2025-10-31 0:30 ` [PATCH v4 1/8] x86/bugs: Use VM_CLEAR_CPU_BUFFERS in VMX as well Sean Christopherson
2025-10-31 11:30 ` Brendan Jackman
2025-11-01 1:46 ` Pawan Gupta
2025-11-03 18:18 ` Pawan Gupta
2025-11-07 19:05 ` Borislav Petkov
2025-11-11 22:03 ` Sean Christopherson [this message]
2025-11-12 10:23 ` Borislav Petkov
2025-11-12 18:19 ` Pawan Gupta
2025-11-12 18:17 ` Pawan Gupta
2025-11-07 18:59 ` Borislav Petkov
2025-11-12 18:02 ` Pawan Gupta
2025-10-31 0:30 ` [PATCH v4 2/8] x86/bugs: Decouple ALTERNATIVE usage from VERW macro definition Sean Christopherson
2025-10-31 11:37 ` Brendan Jackman
2025-10-31 17:43 ` Sean Christopherson
2025-11-01 4:13 ` Pawan Gupta
2025-11-03 17:00 ` Sean Christopherson
2025-11-03 17:40 ` Pawan Gupta
2025-11-12 12:15 ` Borislav Petkov
2025-10-31 0:30 ` [PATCH v4 3/8] x86/bugs: Use an X86_FEATURE_xxx flag for the MMIO Stale Data mitigation Sean Christopherson
2025-10-31 11:44 ` Brendan Jackman
2025-10-31 21:47 ` Sean Christopherson
2025-11-03 10:49 ` Brendan Jackman
2025-10-31 22:28 ` Pawan Gupta
2025-10-31 22:37 ` Sean Christopherson
2025-10-31 22:50 ` Pawan Gupta
2025-11-12 14:46 ` Borislav Petkov
2025-11-12 18:24 ` Pawan Gupta
2025-10-31 0:30 ` [PATCH v4 4/8] KVM: VMX: Handle MMIO Stale Data in VM-Enter assembly via ALTERNATIVES_2 Sean Christopherson
2025-10-31 12:32 ` Brendan Jackman
2025-10-31 21:44 ` Sean Christopherson
2025-11-03 10:51 ` Brendan Jackman
2025-10-31 23:55 ` Pawan Gupta
2025-11-01 3:41 ` Pawan Gupta
2025-11-03 9:17 ` Peter Zijlstra
2025-11-03 17:37 ` Pawan Gupta
2025-11-03 17:46 ` Pawan Gupta
2025-11-12 16:41 ` Borislav Petkov
2025-11-12 17:15 ` Sean Christopherson
2025-11-12 18:38 ` Borislav Petkov
2025-11-12 20:30 ` Sean Christopherson
2025-11-12 23:01 ` Pawan Gupta
2025-11-13 14:20 ` Borislav Petkov
2025-11-13 22:01 ` Sean Christopherson
2025-10-31 0:30 ` [PATCH v4 5/8] x86/bugs: KVM: Move VM_CLEAR_CPU_BUFFERS into SVM as SVM_CLEAR_CPU_BUFFERS Sean Christopherson
2025-10-31 12:34 ` Brendan Jackman
2025-11-13 15:03 ` Borislav Petkov
2025-11-13 15:37 ` Sean Christopherson
2025-11-13 16:19 ` Borislav Petkov
2025-10-31 0:30 ` [PATCH v4 6/8] KVM: VMX: Bundle all L1 data cache flush mitigation code together Sean Christopherson
2025-11-03 18:26 ` Pawan Gupta
2025-10-31 0:30 ` [PATCH v4 7/8] KVM: VMX: Disable L1TF L1 data cache flush if CONFIG_CPU_MITIGATIONS=n Sean Christopherson
2025-10-31 12:37 ` Brendan Jackman
2025-10-31 0:30 ` [PATCH v4 8/8] KVM: x86: Unify L1TF flushing under per-CPU variable Sean Christopherson
2025-10-31 11:22 ` [PATCH v4 0/8] x86/bugs: KVM: L1TF and MMIO Stale Data cleanups Brendan Jackman
2025-10-31 17:36 ` Sean Christopherson
2025-11-04 10:58 ` Brendan Jackman
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