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Subject[PATCH 4.9 74/87] x86/cpufeatures: Disentangle SSBD enumeration
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Thomas Gleixner <tglx@linutronix.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@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/cpufeatures.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/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -198,6 +198,7 @@
#define X86_FEATURE_RETPOLINE_AMD ( 7*32+13) /* "" AMD Retpoline mitigation for Spectre variant 2 */

#define X86_FEATURE_MSR_SPEC_CTRL ( 7*32+16) /* "" MSR SPEC_CTRL is implemented */
+#define X86_FEATURE_SSBD ( 7*32+17) /* Speculative Store Bypass Disable */

#define X86_FEATURE_RSB_CTXSW ( 7*32+19) /* "" Fill RSB on context switches */

@@ -207,7 +208,7 @@
#define X86_FEATURE_USE_IBPB ( 7*32+21) /* "" Indirect Branch Prediction Barrier enabled */
#define X86_FEATURE_USE_IBRS_FW ( 7*32+22) /* "" Use IBRS during runtime firmware calls */
#define X86_FEATURE_SPEC_STORE_BYPASS_DISABLE ( 7*32+23) /* "" Disable Speculative Store Bypass. */
-#define X86_FEATURE_AMD_SSBD ( 7*32+24) /* "" AMD SSBD implementation */
+#define X86_FEATURE_LS_CFG_SSBD ( 7*32+24) /* "" AMD SSBD implementation */
#define X86_FEATURE_IBRS ( 7*32+25) /* Indirect Branch Restricted Speculation */
#define X86_FEATURE_IBPB ( 7*32+26) /* Indirect Branch Prediction Barrier */
#define X86_FEATURE_STIBP ( 7*32+27) /* Single Thread Indirect Branch Predictors */
@@ -314,7 +315,7 @@
#define X86_FEATURE_SPEC_CTRL (18*32+26) /* "" Speculation Control (IBRS + IBPB) */
#define X86_FEATURE_INTEL_STIBP (18*32+27) /* "" Single Thread Indirect Branch Predictors */
#define X86_FEATURE_ARCH_CAPABILITIES (18*32+29) /* IA32_ARCH_CAPABILITIES MSR (Intel) */
-#define X86_FEATURE_SSBD (18*32+31) /* Speculative Store Bypass Disable */
+#define X86_FEATURE_SPEC_CTRL_SSBD (18*32+31) /* "" Speculative Store Bypass Disable */

/*
* BUG word(s)
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -558,8 +558,8 @@ 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;
}
}
@@ -848,11 +848,6 @@ static void init_amd(struct cpuinfo_x86
/* AMD CPUs don't reset SS attributes on SYSRET, Xen does. */
if (!cpu_has(c, X86_FEATURE_XENPV))
set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
-
- 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
@@ -158,8 +158,8 @@ 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)
@@ -175,8 +175,8 @@ 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)
@@ -188,7 +188,7 @@ 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
@@ -735,6 +735,9 @@ 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
@@ -156,6 +156,7 @@ 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
@@ -207,7 +207,7 @@ 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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