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Date:   Sat, 29 Sep 2018 22:43:07 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>,
        "Borislav Petkov" <bp@...e.de>,
        "David Woodhouse" <dwmw@...zon.co.uk>
Subject: [PATCH 3.16 035/131] x86/cpufeatures: Disentangle SSBD enumeration

3.16.59-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Thomas Gleixner <tglx@...utronix.de>

commit 52817587e706686fcdb27f14c1b000c92f266c96 upstream.

The SSBD enumeration is similarly to the other bits magically shared
between Intel and AMD though the mechanisms are different.

Make X86_FEATURE_SSBD synthetic and set it depending on the vendor specific
features or family dependent setup.

Change the Intel bit to X86_FEATURE_SPEC_CTRL_SSBD to denote that SSBD is
controlled via MSR_SPEC_CTRL and fix up the usage sites.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[bwh: Backported to 3.16:
 - Use the next available bit number in CPU feature word 7
 - Adjust filename, context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/include/asm/cpufeature.h |  5 +++--
 arch/x86/kernel/cpu/amd.c         |  7 +------
 arch/x86/kernel/cpu/bugs.c        | 10 +++++-----
 arch/x86/kernel/cpu/common.c      |  3 +++
 arch/x86/kernel/cpu/intel.c       |  1 +
 arch/x86/kernel/process.c         |  2 +-
 6 files changed, 14 insertions(+), 14 deletions(-)

--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -192,11 +192,12 @@
 #define X86_FEATURE_USE_IBPB	(7*32+12) /* "" Indirect Branch Prediction Barrier enabled */
 #define X86_FEATURE_USE_IBRS_FW (7*32+13) /* "" Use IBRS during runtime firmware calls */
 #define X86_FEATURE_SPEC_STORE_BYPASS_DISABLE (7*32+14) /* "" Disable Speculative Store Bypass. */
-#define X86_FEATURE_AMD_SSBD	(7*32+15)  /* "" AMD SSBD implementation */
+#define X86_FEATURE_LS_CFG_SSBD	(7*32+15) /* "" AMD SSBD implementation */
 #define X86_FEATURE_IBRS	(7*32+16) /* Indirect Branch Restricted Speculation */
 #define X86_FEATURE_IBPB	(7*32+17) /* Indirect Branch Prediction Barrier */
 #define X86_FEATURE_STIBP	(7*32+18) /* Single Thread Indirect Branch Predictors */
 #define X86_FEATURE_MSR_SPEC_CTRL (7*32+19) /* "" MSR SPEC_CTRL is implemented */
+#define X86_FEATURE_SSBD	(7*32+20) /* Speculative Store Bypass Disable */
 
 #define X86_FEATURE_RETPOLINE	(7*32+29) /* "" Generic Retpoline mitigation for Spectre variant 2 */
 #define X86_FEATURE_RETPOLINE_AMD (7*32+30) /* "" AMD Retpoline mitigation for Spectre variant 2 */
@@ -247,7 +248,7 @@
 #define X86_FEATURE_SPEC_CTRL		(10*32+26) /* "" Speculation Control (IBRS + IBPB) */
 #define X86_FEATURE_INTEL_STIBP		(10*32+27) /* "" Single Thread Indirect Branch Predictors */
 #define X86_FEATURE_ARCH_CAPABILITIES	(10*32+29) /* IA32_ARCH_CAPABILITIES MSR (Intel) */
-#define X86_FEATURE_SSBD		(10*32+31) /* Speculative Store Bypass Disable */
+#define X86_FEATURE_SPEC_CTRL_SSBD	(10*32+31) /* "" Speculative Store Bypass Disable */
 
 /* AMD-defined CPU features, CPUID level 0x80000008 (EBX), word 11 */
 #define X86_FEATURE_AMD_IBPB		(11*32+12) /* Indirect Branch Prediction Barrier */
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -486,8 +486,8 @@ static void bsp_init_amd(struct cpuinfo_
 		 * avoid RMW. If that faults, do not enable SSBD.
 		 */
 		if (!rdmsrl_safe(MSR_AMD64_LS_CFG, &x86_amd_ls_cfg_base)) {
+			setup_force_cpu_cap(X86_FEATURE_LS_CFG_SSBD);
 			setup_force_cpu_cap(X86_FEATURE_SSBD);
-			setup_force_cpu_cap(X86_FEATURE_AMD_SSBD);
 			x86_amd_ls_cfg_ssbd_mask = 1ULL << bit;
 		}
 	}
@@ -801,11 +801,6 @@ static void init_amd(struct cpuinfo_x86
 		set_cpu_bug(c, X86_BUG_AMD_APIC_C1E);
 
 	rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy);
-
-	if (boot_cpu_has(X86_FEATURE_AMD_SSBD)) {
-		set_cpu_cap(c, X86_FEATURE_SSBD);
-		set_cpu_cap(c, X86_FEATURE_AMD_SSBD);
-	}
 }
 
 #ifdef CONFIG_X86_32
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -220,8 +220,8 @@ void x86_spec_ctrl_set_guest(u64 guest_s
 	if (!static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
 		return;
 
-	/* Intel controls SSB in MSR_SPEC_CTRL */
-	if (static_cpu_has(X86_FEATURE_SPEC_CTRL))
+	/* SSBD controlled in MSR_SPEC_CTRL */
+	if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD))
 		host |= ssbd_tif_to_spec_ctrl(current_thread_info()->flags);
 
 	if (host != guest_spec_ctrl)
@@ -237,8 +237,8 @@ void x86_spec_ctrl_restore_host(u64 gues
 	if (!static_cpu_has(X86_FEATURE_MSR_SPEC_CTRL))
 		return;
 
-	/* Intel controls SSB in MSR_SPEC_CTRL */
-	if (static_cpu_has(X86_FEATURE_SPEC_CTRL))
+	/* SSBD controlled in MSR_SPEC_CTRL */
+	if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD))
 		host |= ssbd_tif_to_spec_ctrl(current_thread_info()->flags);
 
 	if (host != guest_spec_ctrl)
@@ -250,7 +250,7 @@ static void x86_amd_ssb_disable(void)
 {
 	u64 msrval = x86_amd_ls_cfg_base | x86_amd_ls_cfg_ssbd_mask;
 
-	if (boot_cpu_has(X86_FEATURE_AMD_SSBD))
+	if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD))
 		wrmsrl(MSR_AMD64_LS_CFG, msrval);
 }
 
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -700,6 +700,9 @@ static void init_speculation_control(str
 	if (cpu_has(c, X86_FEATURE_INTEL_STIBP))
 		set_cpu_cap(c, X86_FEATURE_STIBP);
 
+	if (cpu_has(c, X86_FEATURE_SPEC_CTRL_SSBD))
+		set_cpu_cap(c, X86_FEATURE_SSBD);
+
 	if (cpu_has(c, X86_FEATURE_AMD_IBRS)) {
 		set_cpu_cap(c, X86_FEATURE_IBRS);
 		set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL);
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -122,6 +122,7 @@ static void early_init_intel(struct cpui
 		setup_clear_cpu_cap(X86_FEATURE_MSR_SPEC_CTRL);
 		setup_clear_cpu_cap(X86_FEATURE_INTEL_STIBP);
 		setup_clear_cpu_cap(X86_FEATURE_SSBD);
+		setup_clear_cpu_cap(X86_FEATURE_SPEC_CTRL_SSBD);
 	}
 
 	/*
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -221,7 +221,7 @@ static __always_inline void __speculativ
 {
 	u64 msr;
 
-	if (static_cpu_has(X86_FEATURE_AMD_SSBD)) {
+	if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD)) {
 		msr = x86_amd_ls_cfg_base | ssbd_tif_to_amd_ls_cfg(tifn);
 		wrmsrl(MSR_AMD64_LS_CFG, msr);
 	} else {

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