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.

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index b9d35b6b19f7893f74f83973140a876ea1e7de4a..87e3da7b0439790dac6b35aa4f95e8e7573284d7 100644 (file)
--- 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 cab20216921b56e727b422243a205714182a510e..727b6551e1dfc0483bc3514e6ddfd52495f01b4d 100644 (file)
--- 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 b816506783755a1ce87d511014c9903fe3e25798..aadefcaa9561d0a31e589784da7e871e4a0de2e0 100644 (file)
--- 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 ef2ebabb059c8cdf2f88eb7b98682e29940e4dd8..9499f9c6b07711bb1254ce574584ebc166d293fc 100644 (file)
--- 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 be275a0410a89957e79ffe57747e50ed36876e2f..906ecd001511355d0939e4e90a3994a7bd9809e3 100644 (file)
--- 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 b6fca43cb455d20d9f81eb2f9c1ed0adb6f04bc1..4f4248c2941abd22dd9b097ff937b569bf4b679f 100644 (file)
--- 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)