linux-kernel - [PATCH 4.4 60/88] x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP

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Date:   Fri, 14 Dec 2018 13:00:34 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Jörg Otte <jrg.otte@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>
Subject: [PATCH 4.4 60/88] x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Borislav Petkov <bp@...e.de>

commit e7c587da125291db39ddf1f49b18e5970adbac17 upstream.

Intel and AMD have different CPUID bits hence for those use synthetic bits
which get set on the respective vendor's in init_speculation_control(). So
that debacles like what the commit message of

  c65732e4f721 ("x86/cpu: Restore CPUID_8000_0008_EBX reload")

talks about don't happen anymore.

Signed-off-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Tested-by: Jörg Otte <jrg.otte@...il.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Link: https://lkml.kernel.org/r/20180504161815.GG9257@pd.tnic
Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[bwh: Backported to 4.4: This was partly applied before; apply just the
 missing bits]
Signed-off-by: Ben Hutchings <ben.hutchings@...ethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kvm/cpuid.c |   10 +++++-----
 arch/x86/kvm/cpuid.h |    4 ++--
 2 files changed, 7 insertions(+), 7 deletions(-)

--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -343,7 +343,7 @@ static inline int __do_cpuid_ent(struct
 
 	/* cpuid 0x80000008.ebx */
 	const u32 kvm_cpuid_8000_0008_ebx_x86_features =
-		F(IBPB) | F(IBRS);
+		F(AMD_IBPB) | F(AMD_IBRS);
 
 	/* cpuid 0xC0000001.edx */
 	const u32 kvm_supported_word5_x86_features =
@@ -596,10 +596,10 @@ static inline int __do_cpuid_ent(struct
 		entry->eax = g_phys_as | (virt_as << 8);
 		entry->edx = 0;
 		/* IBRS and IBPB aren't necessarily present in hardware cpuid */
-		if (boot_cpu_has(X86_FEATURE_IBPB))
-			entry->ebx |= F(IBPB);
-		if (boot_cpu_has(X86_FEATURE_IBRS))
-			entry->ebx |= F(IBRS);
+		if (boot_cpu_has(X86_FEATURE_AMD_IBPB))
+			entry->ebx |= F(AMD_IBPB);
+		if (boot_cpu_has(X86_FEATURE_AMD_IBRS))
+			entry->ebx |= F(AMD_IBRS);
 		entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
 		cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
 		break;
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -164,7 +164,7 @@ static inline bool guest_cpuid_has_ibpb(
 	struct kvm_cpuid_entry2 *best;
 
 	best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
-	if (best && (best->ebx & bit(X86_FEATURE_IBPB)))
+	if (best && (best->ebx & bit(X86_FEATURE_AMD_IBPB)))
 		return true;
 	best = kvm_find_cpuid_entry(vcpu, 7, 0);
 	return best && (best->edx & bit(X86_FEATURE_SPEC_CTRL));
@@ -175,7 +175,7 @@ static inline bool guest_cpuid_has_spec_
 	struct kvm_cpuid_entry2 *best;
 
 	best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
-	if (best && (best->ebx & bit(X86_FEATURE_IBRS)))
+	if (best && (best->ebx & bit(X86_FEATURE_AMD_IBRS)))
 		return true;
 	best = kvm_find_cpuid_entry(vcpu, 7, 0);
 	return best && (best->edx & (bit(X86_FEATURE_SPEC_CTRL) | bit(X86_FEATURE_SPEC_CTRL_SSBD)));