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authorTom Lendacky <thomas.lendacky@amd.com>2018-05-17 17:09:18 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-05-22 18:54:06 +0200
commit8e1c285a050ca8bcbe30c47f102497e44319f12c (patch)
treed526f661daad8d214df3e616c7fadb5c87dae6bf
parent72f46c229ac286c0a734888f50a3af274036290f (diff)
x86/speculation: Add virtualized speculative store bypass disable support
commit 11fb0683493b2da112cd64c9dada221b52463bf7 upstream Some AMD processors only support a non-architectural means of enabling speculative store bypass disable (SSBD). To allow a simplified view of this to a guest, an architectural definition has been created through a new CPUID bit, 0x80000008_EBX[25], and a new MSR, 0xc001011f. With this, a hypervisor can virtualize the existence of this definition and provide an architectural method for using SSBD to a guest. Add the new CPUID feature, the new MSR and update the existing SSBD support to use this MSR when present. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov <bp@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/include/asm/cpufeatures.h1
-rw-r--r--arch/x86/include/asm/msr-index.h2
-rw-r--r--arch/x86/kernel/cpu/bugs.c4
-rw-r--r--arch/x86/kernel/process.c13
4 files changed, 18 insertions, 2 deletions
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 8d3cd2e4428d..403e97d5e243 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -282,6 +282,7 @@
#define X86_FEATURE_AMD_IBPB (13*32+12) /* "" Indirect Branch Prediction Barrier */
#define X86_FEATURE_AMD_IBRS (13*32+14) /* "" Indirect Branch Restricted Speculation */
#define X86_FEATURE_AMD_STIBP (13*32+15) /* "" Single Thread Indirect Branch Predictors */
+#define X86_FEATURE_VIRT_SSBD (13*32+25) /* Virtualized Speculative Store Bypass Disable */
/* Thermal and Power Management Leaf, CPUID level 0x00000006 (EAX), word 14 */
#define X86_FEATURE_DTHERM (14*32+ 0) /* Digital Thermal Sensor */
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index b368f6050b8a..44af6ce41e9d 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -344,6 +344,8 @@
#define MSR_AMD64_IBSOPDATA4 0xc001103d
#define MSR_AMD64_IBS_REG_COUNT_MAX 8 /* includes MSR_AMD64_IBSBRTARGET */
+#define MSR_AMD64_VIRT_SPEC_CTRL 0xc001011f
+
/* Fam 17h MSRs */
#define MSR_F17H_IRPERF 0xc00000e9
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index d3afd38f30d1..82422a04b506 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -205,7 +205,9 @@ 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_LS_CFG_SSBD))
+ if (boot_cpu_has(X86_FEATURE_VIRT_SSBD))
+ wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, SPEC_CTRL_SSBD);
+ else if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD))
wrmsrl(MSR_AMD64_LS_CFG, msrval);
}
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 4704a8447a77..70f129dcc66f 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -389,6 +389,15 @@ static __always_inline void amd_set_core_ssb_state(unsigned long tifn)
}
#endif
+static __always_inline void amd_set_ssb_virt_state(unsigned long tifn)
+{
+ /*
+ * SSBD has the same definition in SPEC_CTRL and VIRT_SPEC_CTRL,
+ * so ssbd_tif_to_spec_ctrl() just works.
+ */
+ wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, ssbd_tif_to_spec_ctrl(tifn));
+}
+
static __always_inline void intel_set_ssb_state(unsigned long tifn)
{
u64 msr = x86_spec_ctrl_base | ssbd_tif_to_spec_ctrl(tifn);
@@ -398,7 +407,9 @@ static __always_inline void intel_set_ssb_state(unsigned long tifn)
static __always_inline void __speculative_store_bypass_update(unsigned long tifn)
{
- if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD))
+ if (static_cpu_has(X86_FEATURE_VIRT_SSBD))
+ amd_set_ssb_virt_state(tifn);
+ else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD))
amd_set_core_ssb_state(tifn);
else
intel_set_ssb_state(tifn);