From: Tim Chen <tim.c.chen@linux.intel.com>
To: David Woodhouse <dwmw@amazon.co.uk>,
arjan@linux.intel.com, tglx@linutronix.de, karahmed@amazon.de,
x86@kernel.org, linux-kernel@vger.kernel.org, bp@alien8.de,
peterz@infradead.org, pbonzini@redhat.com, ak@linux.intel.com,
torvalds@linux-foundation.org, gregkh@linux-foundation.org,
dave.hansen@intel.com, gnomes@lxorguk.ukuu.org.uk,
ashok.raj@intel.com, mingo@kernel.org
Subject: Re: [PATCH v5 7/7] x86/speculation: Add basic IBPB (Indirect Branch Prediction Barrier) support
Date: Fri, 26 Jan 2018 13:36:05 -0800 [thread overview]
Message-ID: <85fc729e-6ff6-3a13-481c-2e0e11407225@linux.intel.com> (raw)
In-Reply-To: <1516896855-7642-8-git-send-email-dwmw@amazon.co.uk>
On 01/25/2018 08:14 AM, David Woodhouse wrote:
>
> diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
> index 4ad4108..34e384c 100644
> --- a/arch/x86/include/asm/nospec-branch.h
> +++ b/arch/x86/include/asm/nospec-branch.h
> @@ -218,5 +218,18 @@ static inline void vmexit_fill_RSB(void)
> #endif
> }
>
> +static inline void indirect_branch_prediction_barrier(void)
> +{
> + asm volatile(ALTERNATIVE("",
> + "movl %[msr], %%ecx\n\t"
> + "movl %[val], %%eax\n\t"
> + "movl $0, %%edx\n\t"
> + "wrmsr",
> + X86_FEATURE_IBPB)
> + : : [msr] "i" (MSR_IA32_PRED_CMD),
> + [val] "i" (PRED_CMD_IBPB)
> + : "eax", "ecx", "edx", "memory");
With Peter's fixing of paravirt's indirect call for wrmsr,
(https://patchwork.kernel.org/patch/10173547/)
we don't have to worry about indirect call in wrmsr anymore.
Can we use regular wrmsr here?
It will make IBPB tracing straightforward using the
MSR tracepoints.
Tim
prev parent reply other threads:[~2018-01-26 21:36 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-25 16:14 [PATCH v5 0/7] Basic Speculation Control feature support David Woodhouse
2018-01-25 16:14 ` [PATCH v5 1/7] x86/cpufeatures: Add CPUID_7_EDX CPUID leaf David Woodhouse
2018-01-26 14:59 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-25 16:14 ` [PATCH v5 2/7] x86/cpufeatures: Add Intel feature bits for Speculation Control David Woodhouse
2018-01-26 15:00 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-25 16:14 ` [PATCH v5 3/7] x86/cpufeatures: Add AMD " David Woodhouse
2018-01-25 21:30 ` Borislav Petkov
2018-01-25 21:37 ` Thomas Gleixner
2018-01-25 21:41 ` Borislav Petkov
2018-01-26 15:00 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-26 18:41 ` [PATCH] x86/cpufeatures: Cleanup AMD speculation feature bits Borislav Petkov
2018-01-26 18:45 ` David Woodhouse
2018-01-26 18:49 ` Borislav Petkov
2018-01-26 21:06 ` Tom Lendacky
2018-01-26 21:52 ` Borislav Petkov
2018-01-26 21:59 ` David Woodhouse
2018-01-26 22:10 ` Borislav Petkov
2018-01-26 23:14 ` Tom Lendacky
2018-01-27 8:49 ` David Woodhouse
2018-01-27 9:27 ` David Woodhouse
2018-01-27 9:37 ` Borislav Petkov
2018-01-27 10:32 ` David Woodhouse
2018-01-27 13:18 ` Borislav Petkov
2018-01-25 16:14 ` [PATCH v5 4/7] x86/msr: Add definitions for new speculation control MSRs David Woodhouse
2018-01-26 15:00 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-25 16:14 ` [PATCH v5 5/7] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown David Woodhouse
2018-01-25 18:10 ` Dave Hansen
2018-01-25 19:53 ` Dave Hansen
2018-01-25 22:00 ` Borislav Petkov
2018-01-26 15:01 ` [tip:x86/pti] x86/pti: Do not enable PTI on CPUs " tip-bot for David Woodhouse
2018-01-25 16:14 ` [PATCH v5 6/7] x86/cpufeature: Blacklist SPEC_CTRL/PRED_CMD on early Spectre v2 microcodes David Woodhouse
2018-01-26 15:01 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-25 16:14 ` [PATCH v5 7/7] x86/speculation: Add basic IBPB (Indirect Branch Prediction Barrier) support David Woodhouse
2018-01-26 15:02 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-26 16:18 ` David Woodhouse
2018-01-26 21:36 ` Tim Chen [this message]
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