From a508cec6e5215a3fbc7e73ae86a5c5602187934d Mon Sep 17 00:00:00 2001 From: Pawan Gupta Date: Thu, 14 Aug 2025 10:20:42 -0700 Subject: x86/vmscape: Enumerate VMSCAPE bug The VMSCAPE vulnerability may allow a guest to cause Branch Target Injection (BTI) in userspace hypervisors. Kernels (both host and guest) have existing defenses against direct BTI attacks from guests. There are also inter-process BTI mitigations which prevent processes from attacking each other. However, the threat in this case is to a userspace hypervisor within the same process as the attacker. Userspace hypervisors have access to their own sensitive data like disk encryption keys and also typically have access to all guest data. This means guest userspace may use the hypervisor as a confused deputy to attack sensitive guest kernel data. There are no existing mitigations for these attacks. Introduce X86_BUG_VMSCAPE for this vulnerability and set it on affected Intel and AMD CPUs. Signed-off-by: Pawan Gupta Signed-off-by: Dave Hansen Reviewed-by: Borislav Petkov (AMD) --- arch/x86/kernel/cpu/common.c | 65 +++++++++++++++++++++++++++++--------------- 1 file changed, 43 insertions(+), 22 deletions(-) (limited to 'arch/x86/kernel/cpu/common.c') diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 34a054181c4d..2b87c93e6609 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1236,6 +1236,8 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = { #define ITS_NATIVE_ONLY BIT(9) /* CPU is affected by Transient Scheduler Attacks */ #define TSA BIT(10) +/* CPU is affected by VMSCAPE */ +#define VMSCAPE BIT(11) static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = { VULNBL_INTEL_STEPS(INTEL_IVYBRIDGE, X86_STEP_MAX, SRBDS), @@ -1247,44 +1249,55 @@ static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = { VULNBL_INTEL_STEPS(INTEL_BROADWELL_G, X86_STEP_MAX, SRBDS), VULNBL_INTEL_STEPS(INTEL_BROADWELL_X, X86_STEP_MAX, MMIO), VULNBL_INTEL_STEPS(INTEL_BROADWELL, X86_STEP_MAX, SRBDS), - VULNBL_INTEL_STEPS(INTEL_SKYLAKE_X, 0x5, MMIO | RETBLEED | GDS), - VULNBL_INTEL_STEPS(INTEL_SKYLAKE_X, X86_STEP_MAX, MMIO | RETBLEED | GDS | ITS), - VULNBL_INTEL_STEPS(INTEL_SKYLAKE_L, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS), - VULNBL_INTEL_STEPS(INTEL_SKYLAKE, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS), - VULNBL_INTEL_STEPS(INTEL_KABYLAKE_L, 0xb, MMIO | RETBLEED | GDS | SRBDS), - VULNBL_INTEL_STEPS(INTEL_KABYLAKE_L, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS | ITS), - VULNBL_INTEL_STEPS(INTEL_KABYLAKE, 0xc, MMIO | RETBLEED | GDS | SRBDS), - VULNBL_INTEL_STEPS(INTEL_KABYLAKE, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS | ITS), - VULNBL_INTEL_STEPS(INTEL_CANNONLAKE_L, X86_STEP_MAX, RETBLEED), + VULNBL_INTEL_STEPS(INTEL_SKYLAKE_X, 0x5, MMIO | RETBLEED | GDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_SKYLAKE_X, X86_STEP_MAX, MMIO | RETBLEED | GDS | ITS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_SKYLAKE_L, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_SKYLAKE, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_KABYLAKE_L, 0xb, MMIO | RETBLEED | GDS | SRBDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_KABYLAKE_L, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS | ITS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_KABYLAKE, 0xc, MMIO | RETBLEED | GDS | SRBDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_KABYLAKE, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS | ITS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_CANNONLAKE_L, X86_STEP_MAX, RETBLEED | VMSCAPE), VULNBL_INTEL_STEPS(INTEL_ICELAKE_L, X86_STEP_MAX, MMIO | MMIO_SBDS | RETBLEED | GDS | ITS | ITS_NATIVE_ONLY), VULNBL_INTEL_STEPS(INTEL_ICELAKE_D, X86_STEP_MAX, MMIO | GDS | ITS | ITS_NATIVE_ONLY), VULNBL_INTEL_STEPS(INTEL_ICELAKE_X, X86_STEP_MAX, MMIO | GDS | ITS | ITS_NATIVE_ONLY), - VULNBL_INTEL_STEPS(INTEL_COMETLAKE, X86_STEP_MAX, MMIO | MMIO_SBDS | RETBLEED | GDS | ITS), - VULNBL_INTEL_STEPS(INTEL_COMETLAKE_L, 0x0, MMIO | RETBLEED | ITS), - VULNBL_INTEL_STEPS(INTEL_COMETLAKE_L, X86_STEP_MAX, MMIO | MMIO_SBDS | RETBLEED | GDS | ITS), + VULNBL_INTEL_STEPS(INTEL_COMETLAKE, X86_STEP_MAX, MMIO | MMIO_SBDS | RETBLEED | GDS | ITS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_COMETLAKE_L, 0x0, MMIO | RETBLEED | ITS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_COMETLAKE_L, X86_STEP_MAX, MMIO | MMIO_SBDS | RETBLEED | GDS | ITS | VMSCAPE), VULNBL_INTEL_STEPS(INTEL_TIGERLAKE_L, X86_STEP_MAX, GDS | ITS | ITS_NATIVE_ONLY), VULNBL_INTEL_STEPS(INTEL_TIGERLAKE, X86_STEP_MAX, GDS | ITS | ITS_NATIVE_ONLY), VULNBL_INTEL_STEPS(INTEL_LAKEFIELD, X86_STEP_MAX, MMIO | MMIO_SBDS | RETBLEED), VULNBL_INTEL_STEPS(INTEL_ROCKETLAKE, X86_STEP_MAX, MMIO | RETBLEED | GDS | ITS | ITS_NATIVE_ONLY), - VULNBL_INTEL_TYPE(INTEL_ALDERLAKE, ATOM, RFDS), - VULNBL_INTEL_STEPS(INTEL_ALDERLAKE_L, X86_STEP_MAX, RFDS), - VULNBL_INTEL_TYPE(INTEL_RAPTORLAKE, ATOM, RFDS), - VULNBL_INTEL_STEPS(INTEL_RAPTORLAKE_P, X86_STEP_MAX, RFDS), - VULNBL_INTEL_STEPS(INTEL_RAPTORLAKE_S, X86_STEP_MAX, RFDS), - VULNBL_INTEL_STEPS(INTEL_ATOM_GRACEMONT, X86_STEP_MAX, RFDS), + VULNBL_INTEL_TYPE(INTEL_ALDERLAKE, ATOM, RFDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_ALDERLAKE, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_ALDERLAKE_L, X86_STEP_MAX, RFDS | VMSCAPE), + VULNBL_INTEL_TYPE(INTEL_RAPTORLAKE, ATOM, RFDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_RAPTORLAKE, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_RAPTORLAKE_P, X86_STEP_MAX, RFDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_RAPTORLAKE_S, X86_STEP_MAX, RFDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_METEORLAKE_L, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_ARROWLAKE_H, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_ARROWLAKE, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_ARROWLAKE_U, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_LUNARLAKE_M, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_SAPPHIRERAPIDS_X, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_GRANITERAPIDS_X, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_EMERALDRAPIDS_X, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_ATOM_GRACEMONT, X86_STEP_MAX, RFDS | VMSCAPE), VULNBL_INTEL_STEPS(INTEL_ATOM_TREMONT, X86_STEP_MAX, MMIO | MMIO_SBDS | RFDS), VULNBL_INTEL_STEPS(INTEL_ATOM_TREMONT_D, X86_STEP_MAX, MMIO | RFDS), VULNBL_INTEL_STEPS(INTEL_ATOM_TREMONT_L, X86_STEP_MAX, MMIO | MMIO_SBDS | RFDS), VULNBL_INTEL_STEPS(INTEL_ATOM_GOLDMONT, X86_STEP_MAX, RFDS), VULNBL_INTEL_STEPS(INTEL_ATOM_GOLDMONT_D, X86_STEP_MAX, RFDS), VULNBL_INTEL_STEPS(INTEL_ATOM_GOLDMONT_PLUS, X86_STEP_MAX, RFDS), + VULNBL_INTEL_STEPS(INTEL_ATOM_CRESTMONT_X, X86_STEP_MAX, VMSCAPE), VULNBL_AMD(0x15, RETBLEED), VULNBL_AMD(0x16, RETBLEED), - VULNBL_AMD(0x17, RETBLEED | SMT_RSB | SRSO), - VULNBL_HYGON(0x18, RETBLEED | SMT_RSB | SRSO), - VULNBL_AMD(0x19, SRSO | TSA), - VULNBL_AMD(0x1a, SRSO), + VULNBL_AMD(0x17, RETBLEED | SMT_RSB | SRSO | VMSCAPE), + VULNBL_HYGON(0x18, RETBLEED | SMT_RSB | SRSO | VMSCAPE), + VULNBL_AMD(0x19, SRSO | TSA | VMSCAPE), + VULNBL_AMD(0x1a, SRSO | VMSCAPE), {} }; @@ -1543,6 +1556,14 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c) } } + /* + * Set the bug only on bare-metal. A nested hypervisor should already be + * deploying IBPB to isolate itself from nested guests. + */ + if (cpu_matches(cpu_vuln_blacklist, VMSCAPE) && + !boot_cpu_has(X86_FEATURE_HYPERVISOR)) + setup_force_cpu_bug(X86_BUG_VMSCAPE); + if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN)) return; -- cgit v1.2.3 From 8a68d64bb10334426834e8c273319601878e961e Mon Sep 17 00:00:00 2001 From: Pawan Gupta Date: Fri, 29 Aug 2025 15:28:52 -0700 Subject: x86/vmscape: Add old Intel CPUs to affected list These old CPUs are not tested against VMSCAPE, but are likely vulnerable. Signed-off-by: Pawan Gupta Signed-off-by: Dave Hansen --- arch/x86/kernel/cpu/common.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) (limited to 'arch/x86/kernel/cpu/common.c') diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 2b87c93e6609..f98ec9c7fc07 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1240,15 +1240,18 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = { #define VMSCAPE BIT(11) static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = { - VULNBL_INTEL_STEPS(INTEL_IVYBRIDGE, X86_STEP_MAX, SRBDS), - VULNBL_INTEL_STEPS(INTEL_HASWELL, X86_STEP_MAX, SRBDS), - VULNBL_INTEL_STEPS(INTEL_HASWELL_L, X86_STEP_MAX, SRBDS), - VULNBL_INTEL_STEPS(INTEL_HASWELL_G, X86_STEP_MAX, SRBDS), - VULNBL_INTEL_STEPS(INTEL_HASWELL_X, X86_STEP_MAX, MMIO), - VULNBL_INTEL_STEPS(INTEL_BROADWELL_D, X86_STEP_MAX, MMIO), - VULNBL_INTEL_STEPS(INTEL_BROADWELL_G, X86_STEP_MAX, SRBDS), - VULNBL_INTEL_STEPS(INTEL_BROADWELL_X, X86_STEP_MAX, MMIO), - VULNBL_INTEL_STEPS(INTEL_BROADWELL, X86_STEP_MAX, SRBDS), + VULNBL_INTEL_STEPS(INTEL_SANDYBRIDGE_X, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_SANDYBRIDGE, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_IVYBRIDGE_X, X86_STEP_MAX, VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_IVYBRIDGE, X86_STEP_MAX, SRBDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_HASWELL, X86_STEP_MAX, SRBDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_HASWELL_L, X86_STEP_MAX, SRBDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_HASWELL_G, X86_STEP_MAX, SRBDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_HASWELL_X, X86_STEP_MAX, MMIO | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_BROADWELL_D, X86_STEP_MAX, MMIO | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_BROADWELL_X, X86_STEP_MAX, MMIO | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_BROADWELL_G, X86_STEP_MAX, SRBDS | VMSCAPE), + VULNBL_INTEL_STEPS(INTEL_BROADWELL, X86_STEP_MAX, SRBDS | VMSCAPE), VULNBL_INTEL_STEPS(INTEL_SKYLAKE_X, 0x5, MMIO | RETBLEED | GDS | VMSCAPE), VULNBL_INTEL_STEPS(INTEL_SKYLAKE_X, X86_STEP_MAX, MMIO | RETBLEED | GDS | ITS | VMSCAPE), VULNBL_INTEL_STEPS(INTEL_SKYLAKE_L, X86_STEP_MAX, MMIO | RETBLEED | GDS | SRBDS | VMSCAPE), -- cgit v1.2.3