summaryrefslogtreecommitdiff
path: root/arch/x86/kvm
diff options
context:
space:
mode:
authorPaolo Bonzini <pbonzini@redhat.com>2024-01-08 08:10:04 -0500
committerPaolo Bonzini <pbonzini@redhat.com>2024-01-08 08:10:04 -0500
commit33d0403fdad8f4f6a1ccf552bdc31a0170f665b8 (patch)
treeb1ef4af6d024ed17c0e8b8fab932ea76e116eed7 /arch/x86/kvm
parent0afdfd85e33afdbda4cdd219c22ee5bf95b005f4 (diff)
parent15223c4f973a6120665ece9ce1ad17aec0be0e6c (diff)
Merge tag 'kvm-x86-misc-6.8' of https://github.com/kvm-x86/linux into HEAD
KVM x86 misc changes for 6.8: - Turn off KVM_WERROR by default for all configs so that it's not inadvertantly enabled by non-KVM developers, which can be problematic for subsystems that require no regressions for W=1 builds. - Advertise all of the host-supported CPUID bits that enumerate IA32_SPEC_CTRL "features". - Don't force a masterclock update when a vCPU synchronizes to the current TSC generation, as updating the masterclock can cause kvmclock's time to "jump" unexpectedly, e.g. when userspace hotplugs a pre-created vCPU. - Use RIP-relative address to read kvm_rebooting in the VM-Enter fault paths, partly as a super minor optimization, but mostly to make KVM play nice with position independent executable builds.
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/Kconfig14
-rw-r--r--arch/x86/kvm/cpuid.c21
-rw-r--r--arch/x86/kvm/reverse_cpuid.h35
-rw-r--r--arch/x86/kvm/svm/vmenter.S10
-rw-r--r--arch/x86/kvm/vmx/vmenter.S2
-rw-r--r--arch/x86/kvm/x86.c29
6 files changed, 70 insertions, 41 deletions
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index b9d35b6b19f7..87e3da7b0439 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -62,13 +62,13 @@ config KVM
config KVM_WERROR
bool "Compile KVM with -Werror"
- # KASAN may cause the build to fail due to larger frames
- default y if X86_64 && !KASAN
- # We use the dependency on !COMPILE_TEST to not be enabled
- # blindly in allmodconfig or allyesconfig configurations
- depends on KVM
- depends on (X86_64 && !KASAN) || !COMPILE_TEST
- depends on EXPERT
+ # Disallow KVM's -Werror if KASAN is enabled, e.g. to guard against
+ # randomized configs from selecting KVM_WERROR=y, which doesn't play
+ # nice with KASAN. KASAN builds generates warnings for the default
+ # FRAME_WARN, i.e. KVM_WERROR=y with KASAN=y requires special tuning.
+ # Building KVM with -Werror and KASAN is still doable via enabling
+ # the kernel-wide WERROR=y.
+ depends on KVM && EXPERT && !KASAN
help
Add -Werror to the build flags for KVM.
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index cab20216921b..727b6551e1df 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -685,6 +685,11 @@ void kvm_set_cpu_caps(void)
F(AMX_COMPLEX)
);
+ kvm_cpu_cap_init_kvm_defined(CPUID_7_2_EDX,
+ F(INTEL_PSFD) | F(IPRED_CTRL) | F(RRSBA_CTRL) | F(DDPD_U) |
+ F(BHI_CTRL) | F(MCDT_NO)
+ );
+
kvm_cpu_cap_mask(CPUID_D_1_EAX,
F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES) | f_xfd
);
@@ -966,13 +971,13 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
break;
/* function 7 has additional index. */
case 7:
- entry->eax = min(entry->eax, 1u);
+ max_idx = entry->eax = min(entry->eax, 2u);
cpuid_entry_override(entry, CPUID_7_0_EBX);
cpuid_entry_override(entry, CPUID_7_ECX);
cpuid_entry_override(entry, CPUID_7_EDX);
- /* KVM only supports 0x7.0 and 0x7.1, capped above via min(). */
- if (entry->eax == 1) {
+ /* KVM only supports up to 0x7.2, capped above via min(). */
+ if (max_idx >= 1) {
entry = do_host_cpuid(array, function, 1);
if (!entry)
goto out;
@@ -982,6 +987,16 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
entry->ebx = 0;
entry->ecx = 0;
}
+ if (max_idx >= 2) {
+ entry = do_host_cpuid(array, function, 2);
+ if (!entry)
+ goto out;
+
+ cpuid_entry_override(entry, CPUID_7_2_EDX);
+ entry->ecx = 0;
+ entry->ebx = 0;
+ entry->eax = 0;
+ }
break;
case 0xa: { /* Architectural Performance Monitoring */
union cpuid10_eax eax;
diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
index b81650678375..aadefcaa9561 100644
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -16,6 +16,7 @@ enum kvm_only_cpuid_leafs {
CPUID_7_1_EDX,
CPUID_8000_0007_EDX,
CPUID_8000_0022_EAX,
+ CPUID_7_2_EDX,
NR_KVM_CPU_CAPS,
NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
@@ -46,6 +47,14 @@ enum kvm_only_cpuid_leafs {
#define X86_FEATURE_AMX_COMPLEX KVM_X86_FEATURE(CPUID_7_1_EDX, 8)
#define X86_FEATURE_PREFETCHITI KVM_X86_FEATURE(CPUID_7_1_EDX, 14)
+/* Intel-defined sub-features, CPUID level 0x00000007:2 (EDX) */
+#define X86_FEATURE_INTEL_PSFD KVM_X86_FEATURE(CPUID_7_2_EDX, 0)
+#define X86_FEATURE_IPRED_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 1)
+#define KVM_X86_FEATURE_RRSBA_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 2)
+#define X86_FEATURE_DDPD_U KVM_X86_FEATURE(CPUID_7_2_EDX, 3)
+#define X86_FEATURE_BHI_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 4)
+#define X86_FEATURE_MCDT_NO KVM_X86_FEATURE(CPUID_7_2_EDX, 5)
+
/* CPUID level 0x80000007 (EDX). */
#define KVM_X86_FEATURE_CONSTANT_TSC KVM_X86_FEATURE(CPUID_8000_0007_EDX, 8)
@@ -80,6 +89,7 @@ static const struct cpuid_reg reverse_cpuid[] = {
[CPUID_8000_0007_EDX] = {0x80000007, 0, CPUID_EDX},
[CPUID_8000_0021_EAX] = {0x80000021, 0, CPUID_EAX},
[CPUID_8000_0022_EAX] = {0x80000022, 0, CPUID_EAX},
+ [CPUID_7_2_EDX] = { 7, 2, CPUID_EDX},
};
/*
@@ -106,18 +116,19 @@ static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
*/
static __always_inline u32 __feature_translate(int x86_feature)
{
- if (x86_feature == X86_FEATURE_SGX1)
- return KVM_X86_FEATURE_SGX1;
- else if (x86_feature == X86_FEATURE_SGX2)
- return KVM_X86_FEATURE_SGX2;
- else if (x86_feature == X86_FEATURE_SGX_EDECCSSA)
- return KVM_X86_FEATURE_SGX_EDECCSSA;
- else if (x86_feature == X86_FEATURE_CONSTANT_TSC)
- return KVM_X86_FEATURE_CONSTANT_TSC;
- else if (x86_feature == X86_FEATURE_PERFMON_V2)
- return KVM_X86_FEATURE_PERFMON_V2;
-
- return x86_feature;
+#define KVM_X86_TRANSLATE_FEATURE(f) \
+ case X86_FEATURE_##f: return KVM_X86_FEATURE_##f
+
+ switch (x86_feature) {
+ KVM_X86_TRANSLATE_FEATURE(SGX1);
+ KVM_X86_TRANSLATE_FEATURE(SGX2);
+ KVM_X86_TRANSLATE_FEATURE(SGX_EDECCSSA);
+ KVM_X86_TRANSLATE_FEATURE(CONSTANT_TSC);
+ KVM_X86_TRANSLATE_FEATURE(PERFMON_V2);
+ KVM_X86_TRANSLATE_FEATURE(RRSBA_CTRL);
+ default:
+ return x86_feature;
+ }
}
static __always_inline u32 __feature_leaf(int x86_feature)
diff --git a/arch/x86/kvm/svm/vmenter.S b/arch/x86/kvm/svm/vmenter.S
index ef2ebabb059c..9499f9c6b077 100644
--- a/arch/x86/kvm/svm/vmenter.S
+++ b/arch/x86/kvm/svm/vmenter.S
@@ -270,16 +270,16 @@ SYM_FUNC_START(__svm_vcpu_run)
RESTORE_GUEST_SPEC_CTRL_BODY
RESTORE_HOST_SPEC_CTRL_BODY
-10: cmpb $0, kvm_rebooting
+10: cmpb $0, _ASM_RIP(kvm_rebooting)
jne 2b
ud2
-30: cmpb $0, kvm_rebooting
+30: cmpb $0, _ASM_RIP(kvm_rebooting)
jne 4b
ud2
-50: cmpb $0, kvm_rebooting
+50: cmpb $0, _ASM_RIP(kvm_rebooting)
jne 6b
ud2
-70: cmpb $0, kvm_rebooting
+70: cmpb $0, _ASM_RIP(kvm_rebooting)
jne 8b
ud2
@@ -381,7 +381,7 @@ SYM_FUNC_START(__svm_sev_es_vcpu_run)
RESTORE_GUEST_SPEC_CTRL_BODY
RESTORE_HOST_SPEC_CTRL_BODY
-3: cmpb $0, kvm_rebooting
+3: cmpb $0, _ASM_RIP(kvm_rebooting)
jne 2b
ud2
diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S
index be275a0410a8..906ecd001511 100644
--- a/arch/x86/kvm/vmx/vmenter.S
+++ b/arch/x86/kvm/vmx/vmenter.S
@@ -289,7 +289,7 @@ SYM_INNER_LABEL_ALIGN(vmx_vmexit, SYM_L_GLOBAL)
RET
.Lfixup:
- cmpb $0, kvm_rebooting
+ cmpb $0, _ASM_RIP(kvm_rebooting)
jne .Lvmfail
ud2
.Lvmfail:
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b6fca43cb455..4f4248c2941a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2513,26 +2513,29 @@ static inline int gtod_is_based_on_tsc(int mode)
}
#endif
-static void kvm_track_tsc_matching(struct kvm_vcpu *vcpu)
+static void kvm_track_tsc_matching(struct kvm_vcpu *vcpu, bool new_generation)
{
#ifdef CONFIG_X86_64
- bool vcpus_matched;
struct kvm_arch *ka = &vcpu->kvm->arch;
struct pvclock_gtod_data *gtod = &pvclock_gtod_data;
- vcpus_matched = (ka->nr_vcpus_matched_tsc + 1 ==
- atomic_read(&vcpu->kvm->online_vcpus));
+ /*
+ * To use the masterclock, the host clocksource must be based on TSC
+ * and all vCPUs must have matching TSCs. Note, the count for matching
+ * vCPUs doesn't include the reference vCPU, hence "+1".
+ */
+ bool use_master_clock = (ka->nr_vcpus_matched_tsc + 1 ==
+ atomic_read(&vcpu->kvm->online_vcpus)) &&
+ gtod_is_based_on_tsc(gtod->clock.vclock_mode);
/*
- * Once the masterclock is enabled, always perform request in
- * order to update it.
- *
- * In order to enable masterclock, the host clocksource must be TSC
- * and the vcpus need to have matched TSCs. When that happens,
- * perform request to enable masterclock.
+ * Request a masterclock update if the masterclock needs to be toggled
+ * on/off, or when starting a new generation and the masterclock is
+ * enabled (compute_guest_tsc() requires the masterclock snapshot to be
+ * taken _after_ the new generation is created).
*/
- if (ka->use_master_clock ||
- (gtod_is_based_on_tsc(gtod->clock.vclock_mode) && vcpus_matched))
+ if ((ka->use_master_clock && new_generation) ||
+ (ka->use_master_clock != use_master_clock))
kvm_make_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu);
trace_kvm_track_tsc(vcpu->vcpu_id, ka->nr_vcpus_matched_tsc,
@@ -2709,7 +2712,7 @@ static void __kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 offset, u64 tsc,
vcpu->arch.this_tsc_nsec = kvm->arch.cur_tsc_nsec;
vcpu->arch.this_tsc_write = kvm->arch.cur_tsc_write;
- kvm_track_tsc_matching(vcpu);
+ kvm_track_tsc_matching(vcpu, !matched);
}
static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 *user_value)