Merge branch 'kvm-updates/3.3' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Fixing a regression with the PMU MSRs when PMU virtualization is
disabled, a guest-internal DoS with the SYSCALL instruction, and a dirty
memory logging race that may cause live migration to fail.

* 'kvm-updates/3.3' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: do not #GP on perf MSR writes when vPMU is disabled
  KVM: x86: fix missing checks in syscall emulation
  KVM: x86: extend "struct x86_emulate_ops" with "get_cpuid"
  KVM: Fix __set_bit() race in mark_page_dirty() during dirty logging

4 files changed, 113 insertions, 1 deletions

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index ab4092e3214e..7b9cfc4878af 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -190,6 +190,9 @@ struct x86_emulate_ops {
         int (*intercept)(struct x86_emulate_ctxt *ctxt,
                          struct x86_instruction_info *info,
                          enum x86_intercept_stage stage);
+
+        bool (*get_cpuid)(struct x86_emulate_ctxt *ctxt,
+                         u32 *eax, u32 *ebx, u32 *ecx, u32 *edx);
 };
 
 typedef u32 __attribute__((vector_size(16))) sse128_t;
@@ -298,6 +301,19 @@ struct x86_emulate_ctxt {
 #define X86EMUL_MODE_PROT     (X86EMUL_MODE_PROT16|X86EMUL_MODE_PROT32| \
                                X86EMUL_MODE_PROT64)
 
+/* CPUID vendors */
+#define X86EMUL_CPUID_VENDOR_AuthenticAMD_ebx 0x68747541
+#define X86EMUL_CPUID_VENDOR_AuthenticAMD_ecx 0x444d4163
+#define X86EMUL_CPUID_VENDOR_AuthenticAMD_edx 0x69746e65
+
+#define X86EMUL_CPUID_VENDOR_AMDisbetterI_ebx 0x69444d41
+#define X86EMUL_CPUID_VENDOR_AMDisbetterI_ecx 0x21726574
+#define X86EMUL_CPUID_VENDOR_AMDisbetterI_edx 0x74656273
+
+#define X86EMUL_CPUID_VENDOR_GenuineIntel_ebx 0x756e6547
+#define X86EMUL_CPUID_VENDOR_GenuineIntel_ecx 0x6c65746e
+#define X86EMUL_CPUID_VENDOR_GenuineIntel_edx 0x49656e69
+
 enum x86_intercept_stage {
         X86_ICTP_NONE = 0,   /* Allow zero-init to not match anything */
         X86_ICPT_PRE_EXCEPT,
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 05a562b85025..0982507b962a 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1891,6 +1891,51 @@ setup_syscalls_segments(struct x86_emulate_ctxt *ctxt,
         ss->p = 1;
 }
 
+static bool em_syscall_is_enabled(struct x86_emulate_ctxt *ctxt)
+{
+        struct x86_emulate_ops *ops = ctxt->ops;
+        u32 eax, ebx, ecx, edx;
+
+        /*
+         * syscall should always be enabled in longmode - so only become
+         * vendor specific (cpuid) if other modes are active...
+         */
+        if (ctxt->mode == X86EMUL_MODE_PROT64)
+                return true;
+
+        eax = 0x00000000;
+        ecx = 0x00000000;
+        if (ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx)) {
+                /*
+                 * Intel ("GenuineIntel")
+                 * remark: Intel CPUs only support "syscall" in 64bit
+                 * longmode. Also an 64bit guest with a
+                 * 32bit compat-app running will #UD !! While this
+                 * behaviour can be fixed (by emulating) into AMD
+                 * response - CPUs of AMD can't behave like Intel.
+                 */
+                if (ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx &&
+                    ecx == X86EMUL_CPUID_VENDOR_GenuineIntel_ecx &&
+                    edx == X86EMUL_CPUID_VENDOR_GenuineIntel_edx)
+                        return false;
+
+                /* AMD ("AuthenticAMD") */
+                if (ebx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ebx &&
+                    ecx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ecx &&
+                    edx == X86EMUL_CPUID_VENDOR_AuthenticAMD_edx)
+                        return true;
+
+                /* AMD ("AMDisbetter!") */
+                if (ebx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ebx &&
+                    ecx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ecx &&
+                    edx == X86EMUL_CPUID_VENDOR_AMDisbetterI_edx)
+                        return true;
+        }
+
+        /* default: (not Intel, not AMD), apply Intel's stricter rules... */
+        return false;
+}
+
 static int em_syscall(struct x86_emulate_ctxt *ctxt)
 {
         struct x86_emulate_ops *ops = ctxt->ops;
@@ -1904,9 +1949,15 @@ static int em_syscall(struct x86_emulate_ctxt *ctxt)
             ctxt->mode == X86EMUL_MODE_VM86)
                 return emulate_ud(ctxt);
 
+        if (!(em_syscall_is_enabled(ctxt)))
+                return emulate_ud(ctxt);
+
         ops->get_msr(ctxt, MSR_EFER, &efer);
         setup_syscalls_segments(ctxt, &cs, &ss);
 
+        if (!(efer & EFER_SCE))
+                return emulate_ud(ctxt);
+
         ops->get_msr(ctxt, MSR_STAR, &msr_data);
         msr_data >>= 32;
         cs_sel = (u16)(msr_data & 0xfffc);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 14d6cadc4ba6..9cbfc0698118 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1495,6 +1495,8 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
 
 int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 {
+        bool pr = false;
+
         switch (msr) {
         case MSR_EFER:
                 return set_efer(vcpu, data);
@@ -1635,6 +1637,18 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
                 pr_unimpl(vcpu, "unimplemented perfctr wrmsr: "
                         "0x%x data 0x%llx\n", msr, data);
                 break;
+        case MSR_P6_PERFCTR0:
+        case MSR_P6_PERFCTR1:
+                pr = true;
+        case MSR_P6_EVNTSEL0:
+        case MSR_P6_EVNTSEL1:
+                if (kvm_pmu_msr(vcpu, msr))
+                        return kvm_pmu_set_msr(vcpu, msr, data);
+
+                if (pr || data != 0)
+                        pr_unimpl(vcpu, "disabled perfctr wrmsr: "
+                                "0x%x data 0x%llx\n", msr, data);
+                break;
         case MSR_K7_CLK_CTL:
                 /*
                  * Ignore all writes to this no longer documented MSR.
@@ -1835,6 +1849,14 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
         case MSR_FAM10H_MMIO_CONF_BASE:
                 data = 0;
                 break;
+        case MSR_P6_PERFCTR0:
+        case MSR_P6_PERFCTR1:
+        case MSR_P6_EVNTSEL0:
+        case MSR_P6_EVNTSEL1:
+                if (kvm_pmu_msr(vcpu, msr))
+                        return kvm_pmu_get_msr(vcpu, msr, pdata);
+                data = 0;
+                break;
         case MSR_IA32_UCODE_REV:
                 data = 0x100000000ULL;
                 break;
@@ -4180,6 +4202,28 @@ static int emulator_intercept(struct x86_emulate_ctxt *ctxt,
         return kvm_x86_ops->check_intercept(emul_to_vcpu(ctxt), info, stage);
 }
 
+static bool emulator_get_cpuid(struct x86_emulate_ctxt *ctxt,
+                               u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
+{
+        struct kvm_cpuid_entry2 *cpuid = NULL;
+
+        if (eax && ecx)
+                cpuid = kvm_find_cpuid_entry(emul_to_vcpu(ctxt),
+                                            *eax, *ecx);
+
+        if (cpuid) {
+                *eax = cpuid->eax;
+                *ecx = cpuid->ecx;
+                if (ebx)
+                        *ebx = cpuid->ebx;
+                if (edx)
+                        *edx = cpuid->edx;
+                retur