From: David Woodhouse <dwmw@amazon.co.uk>
To: arjan@linux.intel.com, tglx@linutronix.de, karahmed@amazon.de,
x86@kernel.org, linux-kernel@vger.kernel.org,
tim.c.chen@linux.intel.com, bp@alien8.de, peterz@infradead.org,
pbonzini@redhat.com, ak@linux.intel.com,
torvalds@linux-foundation.org, gregkh@linux-foundation.org
Subject: [PATCH 4/4] x86/pti: Do not enable PTI on fixed Intel processors
Date: Sat, 20 Jan 2018 12:03:33 +0000 [thread overview]
Message-ID: <1516449813-7654-5-git-send-email-dwmw@amazon.co.uk> (raw)
In-Reply-To: <1516449813-7654-1-git-send-email-dwmw@amazon.co.uk>
When they advertise the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO
bit set, they don't need KPTI either.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
arch/x86/kernel/cpu/common.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index e5d66e9..80572ae 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -900,8 +900,13 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
setup_force_cpu_cap(X86_FEATURE_ALWAYS);
- if (c->x86_vendor != X86_VENDOR_AMD)
- setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
+ if (c->x86_vendor != X86_VENDOR_AMD) {
+ unsigned long ia32_cap = 0;
+ if (cpu_has(c, X86_FEATURE_ARCH_CAPABILITIES))
+ rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);
+ if (!(ia32_cap & ARCH_CAP_RDCL_NO))
+ setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
+ }
setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
--
2.7.4
next prev parent reply other threads:[~2018-01-20 12:03 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-20 12:03 [PATCH 0/4] Basic Speculation Control feature support David Woodhouse
2018-01-20 12:03 ` [PATCH 1/4] x86/cpufeatures: Add Intel feature bits for Speculation Control David Woodhouse
2018-01-20 20:29 ` Borislav Petkov
2018-01-20 21:51 ` Steven Noonan
2018-01-20 21:57 ` David Woodhouse
2018-01-20 12:03 ` [PATCH 2/4] x86/cpufeatures: Add AMD feature bits for Prediction Command David Woodhouse
2018-01-21 12:16 ` Borislav Petkov
2018-01-21 12:22 ` David Woodhouse
2018-01-21 12:34 ` Borislav Petkov
2018-01-21 12:41 ` David Woodhouse
2018-01-21 17:36 ` Tom Lendacky
2018-01-21 17:51 ` Borislav Petkov
2018-01-20 12:03 ` [PATCH 3/4] x86/msr: Add definitions for new speculation control MSRs David Woodhouse
2018-01-20 12:03 ` David Woodhouse [this message]
2018-01-20 20:08 ` [PATCH 4/4] x86/pti: Do not enable PTI on fixed Intel processors Thomas Gleixner
2018-01-20 20:13 ` Thomas Gleixner
2018-01-20 20:13 ` Woodhouse, David
2018-01-20 20:13 ` Woodhouse, David
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