From adb60371daa606a3b1539cd3cdf70a641764a15c Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sat, 12 May 2018 20:53:14 +0200 Subject: [PATCH] x86/bugs: Remove x86_spec_ctrl_set() x86_spec_ctrl_set() is only used in bugs.c and the extra mask checks there provide no real value as both call sites can just write x86_spec_ctrl_base to MSR_SPEC_CTRL. x86_spec_ctrl_base is valid and does not need any extra masking or checking. Signed-off-by: Thomas Gleixner Reviewed-by: Borislav Petkov Reviewed-by: Konrad Rzeszutek Wilk CVE-2018-3639 (x86) (cherry-picked from commit 4b59bdb569453a60b752b274ca61f009e37f4dae) Signed-off-by: Tyler Hicks Signed-off-by: Stefan Bader --- arch/x86/include/asm/nospec-branch.h | 2 -- arch/x86/kernel/cpu/bugs.c | 13 ++----------- 2 files changed, 2 insertions(+), 13 deletions(-) diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index ef2d6a087ac0..d219cc6f89e5 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -165,8 +165,6 @@ enum spectre_v2_mitigation { SPECTRE_V2_IBRS, }; -extern void x86_spec_ctrl_set(u64); - /* The Speculative Store Bypass disable variants */ enum ssb_mitigation { SPEC_STORE_BYPASS_NONE, diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 3834479e6d56..2c7206fdc09e 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -132,15 +132,6 @@ static const char *spectre_v2_strings[] = { static enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init = SPECTRE_V2_NONE; -void x86_spec_ctrl_set(u64 val) -{ - if (val & x86_spec_ctrl_mask) - WARN_ONCE(1, "SPEC_CTRL MSR value 0x%16llx is unknown.\n", val); - else - wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base | val); -} -EXPORT_SYMBOL_GPL(x86_spec_ctrl_set); - void x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest) { @@ -462,7 +453,7 @@ static enum ssb_mitigation __init __ssb_select_mitigation(void) case X86_VENDOR_INTEL: x86_spec_ctrl_base |= SPEC_CTRL_SSBD; x86_spec_ctrl_mask &= ~SPEC_CTRL_SSBD; - x86_spec_ctrl_set(SPEC_CTRL_SSBD); + wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); break; case X86_VENDOR_AMD: x86_amd_ssb_disable(); @@ -574,7 +565,7 @@ int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which) void x86_spec_ctrl_setup_ap(void) { if (boot_cpu_has(X86_FEATURE_MSR_SPEC_CTRL)) - x86_spec_ctrl_set(x86_spec_ctrl_base & ~x86_spec_ctrl_mask); + wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); if (ssb_mode == SPEC_STORE_BYPASS_DISABLE) x86_amd_ssb_disable(); -- 2.39.2