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x86/speculation/mmio: Reuse SRBDS mitigation for SBDS

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The Shared Buffers Data Sampling (SBDS) variant of Processor MMIO Stale
Data vulnerabilities may expose RDRAND, RDSEED and SGX EGETKEY data.
Mitigation for this is added by a microcode update.

As some of the implications of SBDS are similar to SRBDS, SRBDS mitigation
infrastructure can be leveraged by SBDS. Set X86_BUG_SRBDS and use SRBDS
mitigation.

Mitigation is enabled by default; use srbds=off to opt-out. Mitigation
status can be checked from below file:

  /sys/devices/system/cpu/vulnerabilities/srbds

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Pawan Gupta 2022-05-19 20:34:14 -07:00 committed by Borislav Petkov
parent 22cac9c677
commit a992b8a468
1 changed files with 14 additions and 7 deletions
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21
arch/x86/kernel/cpu/common.c
View File

@ -1239,6 +1239,8 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
#define SRBDS BIT(0)
/* CPU is affected by X86_BUG_MMIO_STALE_DATA */
#define MMIO BIT(1)
/* CPU is affected by Shared Buffers Data Sampling (SBDS), a variant of X86_BUG_MMIO_STALE_DATA */
#define MMIO_SBDS BIT(2)
static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
VULNBL_INTEL_STEPPINGS(IVYBRIDGE, X86_STEPPING_ANY, SRBDS),
@ -1260,16 +1262,17 @@ static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
VULNBL_INTEL_STEPPINGS(KABYLAKE_L, X86_STEPPINGS(0x0, 0x8), SRBDS),
VULNBL_INTEL_STEPPINGS(KABYLAKE, X86_STEPPINGS(0x9, 0xD), SRBDS | MMIO),
VULNBL_INTEL_STEPPINGS(KABYLAKE, X86_STEPPINGS(0x0, 0x8), SRBDS),
VULNBL_INTEL_STEPPINGS(ICELAKE_L, X86_STEPPINGS(0x5, 0x5), MMIO),
VULNBL_INTEL_STEPPINGS(ICELAKE_L, X86_STEPPINGS(0x5, 0x5), MMIO | MMIO_SBDS),
VULNBL_INTEL_STEPPINGS(ICELAKE_D, X86_STEPPINGS(0x1, 0x1), MMIO),
VULNBL_INTEL_STEPPINGS(ICELAKE_X, X86_STEPPINGS(0x4, 0x6), MMIO),
VULNBL_INTEL_STEPPINGS(COMETLAKE, BIT(2) | BIT(3) | BIT(5), MMIO),
VULNBL_INTEL_STEPPINGS(COMETLAKE_L, X86_STEPPINGS(0x0, 0x1), MMIO),
VULNBL_INTEL_STEPPINGS(LAKEFIELD, X86_STEPPINGS(0x1, 0x1), MMIO),
VULNBL_INTEL_STEPPINGS(COMETLAKE, BIT(2) | BIT(3) | BIT(5), MMIO | MMIO_SBDS),
VULNBL_INTEL_STEPPINGS(COMETLAKE_L, X86_STEPPINGS(0x1, 0x1), MMIO | MMIO_SBDS),
VULNBL_INTEL_STEPPINGS(COMETLAKE_L, X86_STEPPINGS(0x0, 0x0), MMIO),
VULNBL_INTEL_STEPPINGS(LAKEFIELD, X86_STEPPINGS(0x1, 0x1), MMIO | MMIO_SBDS),
VULNBL_INTEL_STEPPINGS(ROCKETLAKE, X86_STEPPINGS(0x1, 0x1), MMIO),
VULNBL_INTEL_STEPPINGS(ATOM_TREMONT, X86_STEPPINGS(0x1, 0x1), MMIO),
VULNBL_INTEL_STEPPINGS(ATOM_TREMONT, X86_STEPPINGS(0x1, 0x1), MMIO | MMIO_SBDS),
VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_D, X86_STEPPING_ANY, MMIO),
VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L, X86_STEPPINGS(0x0, 0x0), MMIO),
VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L, X86_STEPPINGS(0x0, 0x0), MMIO | MMIO_SBDS),
{}
};
@ -1350,10 +1353,14 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
/*
* SRBDS affects CPUs which support RDRAND or RDSEED and are listed
* in the vulnerability blacklist.
*
* Some of the implications and mitigation of Shared Buffers Data
* Sampling (SBDS) are similar to SRBDS. Give SBDS same treatment as
* SRBDS.
*/
if ((cpu_has(c, X86_FEATURE_RDRAND) ||
cpu_has(c, X86_FEATURE_RDSEED)) &&
cpu_matches(cpu_vuln_blacklist, SRBDS))
cpu_matches(cpu_vuln_blacklist, SRBDS | MMIO_SBDS))
setup_force_cpu_bug(X86_BUG_SRBDS);
/*