Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b7efb3a6 authored by Pawan Gupta's avatar Pawan Gupta Committed by Greg Kroah-Hartman
Browse files

x86/speculation/mmio: Reuse SRBDS mitigation for SBDS 



commit a992b8a4682f119ae035a01b40d4d0665c4a2875 upstream

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: default avatarPawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
[cascardo: adjust for processor model names]
Signed-off-by: default avatarThadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 48e40e2c

arch/x86/kernel/cpu/common.c

+14 −7
Original line number Diff line number Diff line
@@ -964,6 +964,8 @@ 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),
@@ -985,16 +987,17 @@ static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = { 
	VULNBL_INTEL_STEPPINGS(KABYLAKE_MOBILE,	X86_STEPPINGS(0x0, 0x8),	SRBDS),

	VULNBL_INTEL_STEPPINGS(KABYLAKE_DESKTOP,X86_STEPPINGS(0x9, 0xD),	SRBDS | MMIO),

	VULNBL_INTEL_STEPPINGS(KABYLAKE_DESKTOP,X86_STEPPINGS(0x0, 0x8),	SRBDS),

	VULNBL_INTEL_STEPPINGS(ICELAKE_MOBILE,	X86_STEPPINGS(0x5, 0x5),	MMIO),

	VULNBL_INTEL_STEPPINGS(ICELAKE_MOBILE,	X86_STEPPINGS(0x5, 0x5),	MMIO | MMIO_SBDS),

	VULNBL_INTEL_STEPPINGS(ICELAKE_XEON_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_X,	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),

	{}

};
@@ -1073,10 +1076,14 @@ 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);



	/*