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| author | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2018-04-25 22:04:24 -0400 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-05-03 13:55:49 +0200 |
| commit | 764f3c21588a059cd783c6ba0734d4db2d72822d (patch) | |
| tree | ce5a4674c1c99218da979ade936f043f8ca3c45e /arch/x86/kernel/cpu/amd.c | |
| parent | 1115a859f33276fe8afb31c60cf9d8e657872558 (diff) | |
| download | linux-764f3c21588a059cd783c6ba0734d4db2d72822d.tar.bz2 | |
x86/bugs/AMD: Add support to disable RDS on Fam[15,16,17]h if requested
AMD does not need the Speculative Store Bypass mitigation to be enabled.
The parameters for this are already available and can be done via MSR
C001_1020. Each family uses a different bit in that MSR for this.
[ tglx: Expose the bit mask via a variable and move the actual MSR fiddling
into the bugs code as that's the right thing to do and also required
to prepare for dynamic enable/disable ]
Suggested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/cpu/amd.c')
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 12bc0a1139da..3d553fa5075d 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -10,6 +10,7 @@ #include <asm/processor.h> #include <asm/apic.h> #include <asm/cpu.h> +#include <asm/nospec-branch.h> #include <asm/smp.h> #include <asm/pci-direct.h> #include <asm/delay.h> @@ -554,6 +555,26 @@ static void bsp_init_amd(struct cpuinfo_x86 *c) rdmsrl(MSR_FAM10H_NODE_ID, value); nodes_per_socket = ((value >> 3) & 7) + 1; } + + if (c->x86 >= 0x15 && c->x86 <= 0x17) { + unsigned int bit; + + switch (c->x86) { + case 0x15: bit = 54; break; + case 0x16: bit = 33; break; + case 0x17: bit = 10; break; + default: return; + } + /* + * Try to cache the base value so further operations can + * avoid RMW. If that faults, do not enable RDS. + */ + if (!rdmsrl_safe(MSR_AMD64_LS_CFG, &x86_amd_ls_cfg_base)) { + setup_force_cpu_cap(X86_FEATURE_RDS); + setup_force_cpu_cap(X86_FEATURE_AMD_RDS); + x86_amd_ls_cfg_rds_mask = 1ULL << bit; + } + } } static void early_detect_mem_encrypt(struct cpuinfo_x86 *c) @@ -898,6 +919,11 @@ static void init_amd(struct cpuinfo_x86 *c) /* 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_RDS)) { + set_cpu_cap(c, X86_FEATURE_RDS); + set_cpu_cap(c, X86_FEATURE_AMD_RDS); + } } #ifdef CONFIG_X86_32 |