diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0073-x86-bugs-Expose-x86_spec_ctrl_base-directly.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0073-x86-bugs-Expose-x86_spec_ctrl_base-directly.patch | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0073-x86-bugs-Expose-x86_spec_ctrl_base-directly.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0073-x86-bugs-Expose-x86_spec_ctrl_base-directly.patch new file mode 100644 index 00000000..49224dbb --- /dev/null +++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0073-x86-bugs-Expose-x86_spec_ctrl_base-directly.patch @@ -0,0 +1,120 @@ +From 22a75daea25a170892d8c6cbf0b740ef35219cc8 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Sat, 12 May 2018 20:49:16 +0200 +Subject: [PATCH 73/93] x86/bugs: Expose x86_spec_ctrl_base directly + +commit fa8ac4988249c38476f6ad678a4848a736373403 upstream + +x86_spec_ctrl_base is the system wide default value for the SPEC_CTRL MSR. +x86_spec_ctrl_get_default() returns x86_spec_ctrl_base and was intended to +prevent modification to that variable. Though the variable is read only +after init and globaly visible already. + +Remove the function and export the variable instead. + +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/nospec-branch.h | 16 +++++----------- + arch/x86/include/asm/spec-ctrl.h | 3 --- + arch/x86/kernel/cpu/bugs.c | 11 +---------- + 3 files changed, 6 insertions(+), 24 deletions(-) + +diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h +index bc258e6..8d9deec 100644 +--- a/arch/x86/include/asm/nospec-branch.h ++++ b/arch/x86/include/asm/nospec-branch.h +@@ -217,16 +217,7 @@ enum spectre_v2_mitigation { + SPECTRE_V2_IBRS, + }; + +-/* +- * The Intel specification for the SPEC_CTRL MSR requires that we +- * preserve any already set reserved bits at boot time (e.g. for +- * future additions that this kernel is not currently aware of). +- * We then set any additional mitigation bits that we want +- * ourselves and always use this as the base for SPEC_CTRL. +- * We also use this when handling guest entry/exit as below. +- */ + extern void x86_spec_ctrl_set(u64); +-extern u64 x86_spec_ctrl_get_default(void); + + /* The Speculative Store Bypass disable variants */ + enum ssb_mitigation { +@@ -278,6 +269,9 @@ static inline void indirect_branch_prediction_barrier(void) + alternative_msr_write(MSR_IA32_PRED_CMD, val, X86_FEATURE_USE_IBPB); + } + ++/* The Intel SPEC CTRL MSR base value cache */ ++extern u64 x86_spec_ctrl_base; ++ + /* + * With retpoline, we must use IBRS to restrict branch prediction + * before calling into firmware. +@@ -286,7 +280,7 @@ static inline void indirect_branch_prediction_barrier(void) + */ + #define firmware_restrict_branch_speculation_start() \ + do { \ +- u64 val = x86_spec_ctrl_get_default() | SPEC_CTRL_IBRS; \ ++ u64 val = x86_spec_ctrl_base | SPEC_CTRL_IBRS; \ + \ + preempt_disable(); \ + alternative_msr_write(MSR_IA32_SPEC_CTRL, val, \ +@@ -295,7 +289,7 @@ do { \ + + #define firmware_restrict_branch_speculation_end() \ + do { \ +- u64 val = x86_spec_ctrl_get_default(); \ ++ u64 val = x86_spec_ctrl_base; \ + \ + alternative_msr_write(MSR_IA32_SPEC_CTRL, val, \ + X86_FEATURE_USE_IBRS_FW); \ +diff --git a/arch/x86/include/asm/spec-ctrl.h b/arch/x86/include/asm/spec-ctrl.h +index 9cecbe5..763d497 100644 +--- a/arch/x86/include/asm/spec-ctrl.h ++++ b/arch/x86/include/asm/spec-ctrl.h +@@ -47,9 +47,6 @@ void x86_spec_ctrl_restore_host(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl) + extern u64 x86_amd_ls_cfg_base; + extern u64 x86_amd_ls_cfg_ssbd_mask; + +-/* The Intel SPEC CTRL MSR base value cache */ +-extern u64 x86_spec_ctrl_base; +- + static inline u64 ssbd_tif_to_spec_ctrl(u64 tifn) + { + BUILD_BUG_ON(TIF_SSBD < SPEC_CTRL_SSBD_SHIFT); +diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c +index 9203150..47b7f4f 100644 +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -35,6 +35,7 @@ static void __init ssb_select_mitigation(void); + * writes to SPEC_CTRL contain whatever reserved bits have been set. + */ + u64 __ro_after_init x86_spec_ctrl_base; ++EXPORT_SYMBOL_GPL(x86_spec_ctrl_base); + + /* + * The vendor and possibly platform specific bits which can be modified in +@@ -140,16 +141,6 @@ void x86_spec_ctrl_set(u64 val) + } + EXPORT_SYMBOL_GPL(x86_spec_ctrl_set); + +-u64 x86_spec_ctrl_get_default(void) +-{ +- u64 msrval = x86_spec_ctrl_base; +- +- if (static_cpu_has(X86_FEATURE_SPEC_CTRL)) +- msrval |= ssbd_tif_to_spec_ctrl(current_thread_info()->flags); +- return msrval; +-} +-EXPORT_SYMBOL_GPL(x86_spec_ctrl_get_default); +- + void + x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest) + { +-- +2.7.4 + |