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| author | Tom Lendacky <thomas.lendacky@amd.com> | 2018-05-17 17:09:18 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-05-17 17:09:18 +0200 |
| commit | 11fb0683493b2da112cd64c9dada221b52463bf7 (patch) | |
| tree | 4a1b5caae3b4e322b31d6c7ee4f9c4d6fdd870cb /arch/x86/kernel/process.c | |
| parent | ccbcd2674472a978b48c91c1fbfb66c0ff959f24 (diff) | |
| download | linux-0-day-11fb0683493b2da112cd64c9dada221b52463bf7.tar.gz linux-0-day-11fb0683493b2da112cd64c9dada221b52463bf7.tar.xz | |
x86/speculation: Add virtualized speculative store bypass disable support
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>
Diffstat (limited to 'arch/x86/kernel/process.c')
| -rw-r--r-- | arch/x86/kernel/process.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index d6fe8648d3f6e..91c3398286d84 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -388,6 +388,15 @@ 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); @@ -397,7 +406,9 @@ 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); |