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-rw-r--r--arch/x86/events/core.c12
-rw-r--r--arch/x86/include/asm/cpufeatures.h1
-rw-r--r--arch/x86/include/asm/debugreg.h26
-rw-r--r--arch/x86/include/asm/intel-family.h2
-rw-r--r--arch/x86/kernel/cpu/common.c9
-rw-r--r--arch/x86/kernel/kprobes/core.c2
-rw-r--r--arch/x86/kvm/pmu.h26
-rw-r--r--arch/x86/kvm/x86.c46
-rw-r--r--arch/x86/mm/pat/memtype.c3
9 files changed, 95 insertions, 32 deletions
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 85a63a41c471..d096b04bf80e 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2974,17 +2974,19 @@ unsigned long perf_misc_flags(struct pt_regs *regs)
void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap)
{
- if (!x86_pmu_initialized()) {
+ /* This API doesn't currently support enumerating hybrid PMUs. */
+ if (WARN_ON_ONCE(cpu_feature_enabled(X86_FEATURE_HYBRID_CPU)) ||
+ !x86_pmu_initialized()) {
memset(cap, 0, sizeof(*cap));
return;
}
- cap->version = x86_pmu.version;
/*
- * KVM doesn't support the hybrid PMU yet.
- * Return the common value in global x86_pmu,
- * which available for all cores.
+ * Note, hybrid CPU models get tracked as having hybrid PMUs even when
+ * all E-cores are disabled via BIOS. When E-cores are disabled, the
+ * base PMU holds the correct number of counters for P-cores.
*/
+ cap->version = x86_pmu.version;
cap->num_counters_gp = x86_pmu.num_counters;
cap->num_counters_fixed = x86_pmu.num_counters_fixed;
cap->bit_width_gp = x86_pmu.cntval_bits;
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 61012476d66e..8f39c46197b8 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -466,5 +466,6 @@
#define X86_BUG_MMIO_UNKNOWN X86_BUG(26) /* CPU is too old and its MMIO Stale Data status is unknown */
#define X86_BUG_RETBLEED X86_BUG(27) /* CPU is affected by RETBleed */
#define X86_BUG_EIBRS_PBRSB X86_BUG(28) /* EIBRS is vulnerable to Post Barrier RSB Predictions */
+#define X86_BUG_SMT_RSB X86_BUG(29) /* CPU is vulnerable to Cross-Thread Return Address Predictions */
#endif /* _ASM_X86_CPUFEATURES_H */
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
index b049d950612f..ca97442e8d49 100644
--- a/arch/x86/include/asm/debugreg.h
+++ b/arch/x86/include/asm/debugreg.h
@@ -39,7 +39,20 @@ static __always_inline unsigned long native_get_debugreg(int regno)
asm("mov %%db6, %0" :"=r" (val));
break;
case 7:
- asm("mov %%db7, %0" :"=r" (val));
+ /*
+ * Apply __FORCE_ORDER to DR7 reads to forbid re-ordering them
+ * with other code.
+ *
+ * This is needed because a DR7 access can cause a #VC exception
+ * when running under SEV-ES. Taking a #VC exception is not a
+ * safe thing to do just anywhere in the entry code and
+ * re-ordering might place the access into an unsafe location.
+ *
+ * This happened in the NMI handler, where the DR7 read was
+ * re-ordered to happen before the call to sev_es_ist_enter(),
+ * causing stack recursion.
+ */
+ asm volatile("mov %%db7, %0" : "=r" (val) : __FORCE_ORDER);
break;
default:
BUG();
@@ -66,7 +79,16 @@ static __always_inline void native_set_debugreg(int regno, unsigned long value)
asm("mov %0, %%db6" ::"r" (value));
break;
case 7:
- asm("mov %0, %%db7" ::"r" (value));
+ /*
+ * Apply __FORCE_ORDER to DR7 writes to forbid re-ordering them
+ * with other code.
+ *
+ * While is didn't happen with a DR7 write (see the DR7 read
+ * comment above which explains where it happened), add the
+ * __FORCE_ORDER here too to avoid similar problems in the
+ * future.
+ */
+ asm volatile("mov %0, %%db7" ::"r" (value), __FORCE_ORDER);
break;
default:
BUG();
diff --git a/arch/x86/include/asm/intel-family.h b/arch/x86/include/asm/intel-family.h
index 347707d459c6..cbaf174d8efd 100644
--- a/arch/x86/include/asm/intel-family.h
+++ b/arch/x86/include/asm/intel-family.h
@@ -123,6 +123,8 @@
#define INTEL_FAM6_METEORLAKE 0xAC
#define INTEL_FAM6_METEORLAKE_L 0xAA
+#define INTEL_FAM6_LUNARLAKE_M 0xBD
+
/* "Small Core" Processors (Atom/E-Core) */
#define INTEL_FAM6_ATOM_BONNELL 0x1C /* Diamondville, Pineview */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 9cfca3d7d0e2..f3cc7699e1e1 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1256,6 +1256,8 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
#define MMIO_SBDS BIT(2)
/* CPU is affected by RETbleed, speculating where you would not expect it */
#define RETBLEED BIT(3)
+/* CPU is affected by SMT (cross-thread) return predictions */
+#define SMT_RSB BIT(4)
static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
VULNBL_INTEL_STEPPINGS(IVYBRIDGE, X86_STEPPING_ANY, SRBDS),
@@ -1287,8 +1289,8 @@ static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
VULNBL_AMD(0x15, RETBLEED),
VULNBL_AMD(0x16, RETBLEED),
- VULNBL_AMD(0x17, RETBLEED),
- VULNBL_HYGON(0x18, RETBLEED),
+ VULNBL_AMD(0x17, RETBLEED | SMT_RSB),
+ VULNBL_HYGON(0x18, RETBLEED | SMT_RSB),
{}
};
@@ -1406,6 +1408,9 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
!(ia32_cap & ARCH_CAP_PBRSB_NO))
setup_force_cpu_bug(X86_BUG_EIBRS_PBRSB);
+ if (cpu_matches(cpu_vuln_blacklist, SMT_RSB))
+ setup_force_cpu_bug(X86_BUG_SMT_RSB);
+
if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN))
return;
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index b36f3c367cb2..695873c0f50b 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -625,7 +625,7 @@ static int prepare_emulation(struct kprobe *p, struct insn *insn)
/* 1 byte conditional jump */
p->ainsn.emulate_op = kprobe_emulate_jcc;
p->ainsn.jcc.type = opcode & 0xf;
- p->ainsn.rel32 = *(char *)insn->immediate.bytes;
+ p->ainsn.rel32 = insn->immediate.value;
break;
case 0x0f:
opcode = insn->opcode.bytes[1];
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index cdb91009701d..ee67ba625094 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -165,15 +165,27 @@ static inline void kvm_init_pmu_capability(void)
{
bool is_intel = boot_cpu_data.x86_vendor == X86_VENDOR_INTEL;
- perf_get_x86_pmu_capability(&kvm_pmu_cap);
-
- /*
- * For Intel, only support guest architectural pmu
- * on a host with architectural pmu.
- */
- if ((is_intel && !kvm_pmu_cap.version) || !kvm_pmu_cap.num_counters_gp)
+ /*
+ * Hybrid PMUs don't play nice with virtualization without careful
+ * configuration by userspace, and KVM's APIs for reporting supported
+ * vPMU features do not account for hybrid PMUs. Disable vPMU support
+ * for hybrid PMUs until KVM gains a way to let userspace opt-in.
+ */
+ if (cpu_feature_enabled(X86_FEATURE_HYBRID_CPU))
enable_pmu = false;
+ if (enable_pmu) {
+ perf_get_x86_pmu_capability(&kvm_pmu_cap);
+
+ /*
+ * For Intel, only support guest architectural pmu
+ * on a host with architectural pmu.
+ */
+ if ((is_intel && !kvm_pmu_cap.version) ||
+ !kvm_pmu_cap.num_counters_gp)
+ enable_pmu = false;
+ }
+
if (!enable_pmu) {
memset(&kvm_pmu_cap, 0, sizeof(kvm_pmu_cap));
return;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index da4bbd043a7b..a2c299d47e69 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -191,6 +191,10 @@ module_param(enable_pmu, bool, 0444);
bool __read_mostly eager_page_split = true;
module_param(eager_page_split, bool, 0644);
+/* Enable/disable SMT_RSB bug mitigation */
+bool __read_mostly mitigate_smt_rsb;
+module_param(mitigate_smt_rsb, bool, 0444);
+
/*
* Restoring the host value for MSRs that are only consumed when running in
* usermode, e.g. SYSCALL MSRs and TSC_AUX, can be deferred until the CPU
@@ -4448,10 +4452,15 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
r = KVM_CLOCK_VALID_FLAGS;
break;
case KVM_CAP_X86_DISABLE_EXITS:
- r |= KVM_X86_DISABLE_EXITS_HLT | KVM_X86_DISABLE_EXITS_PAUSE |
- KVM_X86_DISABLE_EXITS_CSTATE;
- if(kvm_can_mwait_in_guest())
- r |= KVM_X86_DISABLE_EXITS_MWAIT;
+ r = KVM_X86_DISABLE_EXITS_PAUSE;
+
+ if (!mitigate_smt_rsb) {
+ r |= KVM_X86_DISABLE_EXITS_HLT |
+ KVM_X86_DISABLE_EXITS_CSTATE;
+
+ if (kvm_can_mwait_in_guest())
+ r |= KVM_X86_DISABLE_EXITS_MWAIT;
+ }
break;
case KVM_CAP_X86_SMM:
if (!IS_ENABLED(CONFIG_KVM_SMM))
@@ -5254,12 +5263,11 @@ static void kvm_vcpu_ioctl_x86_get_debugregs(struct kvm_vcpu *vcpu,
{
unsigned long val;
+ memset(dbgregs, 0, sizeof(*dbgregs));
memcpy(dbgregs->db, vcpu->arch.db, sizeof(vcpu->arch.db));
kvm_get_dr(vcpu, 6, &val);
dbgregs->dr6 = val;
dbgregs->dr7 = vcpu->arch.dr7;
- dbgregs->flags = 0;
- memset(&dbgregs->reserved, 0, sizeof(dbgregs->reserved));
}
static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu,
@@ -6227,15 +6235,26 @@ split_irqchip_unlock:
if (cap->args[0] & ~KVM_X86_DISABLE_VALID_EXITS)
break;
- if ((cap->args[0] & KVM_X86_DISABLE_EXITS_MWAIT) &&
- kvm_can_mwait_in_guest())
- kvm->arch.mwait_in_guest = true;
- if (cap->args[0] & KVM_X86_DISABLE_EXITS_HLT)
- kvm->arch.hlt_in_guest = true;
if (cap->args[0] & KVM_X86_DISABLE_EXITS_PAUSE)
kvm->arch.pause_in_guest = true;
- if (cap->args[0] & KVM_X86_DISABLE_EXITS_CSTATE)
- kvm->arch.cstate_in_guest = true;
+
+#define SMT_RSB_MSG "This processor is affected by the Cross-Thread Return Predictions vulnerability. " \
+ "KVM_CAP_X86_DISABLE_EXITS should only be used with SMT disabled or trusted guests."
+
+ if (!mitigate_smt_rsb) {
+ if (boot_cpu_has_bug(X86_BUG_SMT_RSB) && cpu_smt_possible() &&
+ (cap->args[0] & ~KVM_X86_DISABLE_EXITS_PAUSE))
+ pr_warn_once(SMT_RSB_MSG);
+
+ if ((cap->args[0] & KVM_X86_DISABLE_EXITS_MWAIT) &&
+ kvm_can_mwait_in_guest())
+ kvm->arch.mwait_in_guest = true;
+ if (cap->args[0] & KVM_X86_DISABLE_EXITS_HLT)
+ kvm->arch.hlt_in_guest = true;
+ if (cap->args[0] & KVM_X86_DISABLE_EXITS_CSTATE)
+ kvm->arch.cstate_in_guest = true;
+ }
+
r = 0;
break;
case KVM_CAP_MSR_PLATFORM_INFO:
@@ -13456,6 +13475,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_vmgexit_msr_protocol_exit);
static int __init kvm_x86_init(void)
{
kvm_mmu_x86_module_init();
+ mitigate_smt_rsb &= boot_cpu_has_bug(X86_BUG_SMT_RSB) && cpu_smt_possible();
return 0;
}
module_init(kvm_x86_init);
diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c
index fb4b1b5e0dea..46de9cf5c91d 100644
--- a/arch/x86/mm/pat/memtype.c
+++ b/arch/x86/mm/pat/memtype.c
@@ -387,8 +387,7 @@ static unsigned long pat_x_mtrr_type(u64 start, u64 end,
u8 mtrr_type, uniform;
mtrr_type = mtrr_type_lookup(start, end, &uniform);
- if (mtrr_type != MTRR_TYPE_WRBACK &&
- mtrr_type != MTRR_TYPE_INVALID)
+ if (mtrr_type != MTRR_TYPE_WRBACK)
return _PAGE_CACHE_MODE_UC_MINUS;
return _PAGE_CACHE_MODE_WB;
generated by cgit v1.2.3 (git 2.39.1) at 2025-12-16 03:25:50 +0000