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Diffstat (limited to 'arch/x86/kvm/svm.c')
-rw-r--r--arch/x86/kvm/svm.c158
1 files changed, 156 insertions, 2 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index df7827a981dd..acbde1249b6f 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -37,6 +37,7 @@
#include <asm/desc.h>
#include <asm/debugreg.h>
#include <asm/kvm_para.h>
+#include <asm/microcode.h>
#include <asm/spec-ctrl.h>
#include <asm/virtext.h>
@@ -147,6 +148,14 @@ struct vcpu_svm {
u64 gs_base;
} host;
+ u64 spec_ctrl;
+ /*
+ * Contains guest-controlled bits of VIRT_SPEC_CTRL, which will be
+ * translated into the appropriate L2_CFG bits on the host to
+ * perform speculative control.
+ */
+ u64 virt_spec_ctrl;
+
u32 *msrpm;
ulong nmi_iret_rip;
@@ -182,6 +191,8 @@ static const struct svm_direct_access_msrs {
{ .index = MSR_CSTAR, .always = true },
{ .index = MSR_SYSCALL_MASK, .always = true },
#endif
+ { .index = MSR_IA32_SPEC_CTRL, .always = false },
+ { .index = MSR_IA32_PRED_CMD, .always = false },
{ .index = MSR_IA32_LASTBRANCHFROMIP, .always = false },
{ .index = MSR_IA32_LASTBRANCHTOIP, .always = false },
{ .index = MSR_IA32_LASTINTFROMIP, .always = false },
@@ -411,6 +422,7 @@ struct svm_cpu_data {
struct kvm_ldttss_desc *tss_desc;
struct page *save_area;
+ struct vmcb *current_vmcb;
};
static DEFINE_PER_CPU(struct svm_cpu_data *, svm_data);
@@ -762,6 +774,25 @@ static bool valid_msr_intercept(u32 index)
return false;
}
+static bool msr_write_intercepted(struct kvm_vcpu *vcpu, unsigned msr)
+{
+ u8 bit_write;
+ unsigned long tmp;
+ u32 offset;
+ u32 *msrpm;
+
+ msrpm = is_guest_mode(vcpu) ? to_svm(vcpu)->nested.msrpm:
+ to_svm(vcpu)->msrpm;
+
+ offset = svm_msrpm_offset(msr);
+ bit_write = 2 * (msr & 0x0f) + 1;
+ tmp = msrpm[offset];
+
+ BUG_ON(offset == MSR_INVALID);
+
+ return !!test_bit(bit_write, &tmp);
+}
+
static void set_msr_interception(u32 *msrpm, unsigned msr,
int read, int write)
{
@@ -1120,6 +1151,9 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
u32 dummy;
u32 eax = 1;
+ svm->spec_ctrl = 0;
+ svm->virt_spec_ctrl = 0;
+
if (!init_event) {
svm->vcpu.arch.apic_base = APIC_DEFAULT_PHYS_BASE |
MSR_IA32_APICBASE_ENABLE;
@@ -1210,11 +1244,17 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu)
__free_pages(virt_to_page(svm->nested.msrpm), MSRPM_ALLOC_ORDER);
kvm_vcpu_uninit(vcpu);
kmem_cache_free(kvm_vcpu_cache, svm);
+ /*
+ * The vmcb page can be recycled, causing a false negative in
+ * svm_vcpu_load(). So do a full IBPB now.
+ */
+ indirect_branch_prediction_barrier();
}
static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
+ struct svm_cpu_data *sd = per_cpu(svm_data, cpu);
int i;
if (unlikely(cpu != vcpu->cpu)) {
@@ -1239,6 +1279,10 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
wrmsrl(MSR_AMD64_TSC_RATIO, tsc_ratio);
}
}
+ if (sd->current_vmcb != svm->vmcb) {
+ sd->current_vmcb = svm->vmcb;
+ indirect_branch_prediction_barrier();
+ }
}
static void svm_vcpu_put(struct kvm_vcpu *vcpu)
@@ -2344,6 +2388,14 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
kvm_mmu_reset_context(&svm->vcpu);
kvm_mmu_load(&svm->vcpu);
+ /*
+ * Drop what we picked up for L2 via svm_complete_interrupts() so it
+ * doesn't end up in L1.
+ */
+ svm->vcpu.arch.nmi_injected = false;
+ kvm_clear_exception_queue(&svm->vcpu);
+ kvm_clear_interrupt_queue(&svm->vcpu);
+
return 0;
}
@@ -3051,6 +3103,20 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_VM_CR:
msr_info->data = svm->nested.vm_cr_msr;
break;
+ case MSR_IA32_SPEC_CTRL:
+ if (!msr_info->host_initiated &&
+ !guest_cpuid_has_spec_ctrl(vcpu))
+ return 1;
+
+ msr_info->data = svm->spec_ctrl;
+ break;
+ case MSR_AMD64_VIRT_SPEC_CTRL:
+ if (!msr_info->host_initiated &&
+ !guest_cpuid_has_virt_ssbd(vcpu))
+ return 1;
+
+ msr_info->data = svm->virt_spec_ctrl;
+ break;
case MSR_IA32_UCODE_REV:
msr_info->data = 0x01000065;
break;
@@ -3125,6 +3191,59 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
case MSR_IA32_TSC:
kvm_write_tsc(vcpu, msr);
break;
+ case MSR_IA32_SPEC_CTRL:
+ if (!msr->host_initiated &&
+ !guest_cpuid_has_spec_ctrl(vcpu))
+ return 1;
+
+ /* The STIBP bit doesn't fault even if it's not advertised */
+ if (data & ~(SPEC_CTRL_IBRS | SPEC_CTRL_STIBP))
+ return 1;
+
+ svm->spec_ctrl = data;
+
+ if (!data)
+ break;
+
+ /*
+ * For non-nested:
+ * When it's written (to non-zero) for the first time, pass
+ * it through.
+ *
+ * For nested:
+ * The handling of the MSR bitmap for L2 guests is done in
+ * nested_svm_vmrun_msrpm.
+ * We update the L1 MSR bit as well since it will end up
+ * touching the MSR anyway now.
+ */
+ set_msr_interception(svm->msrpm, MSR_IA32_SPEC_CTRL, 1, 1);
+ break;
+ case MSR_IA32_PRED_CMD:
+ if (!msr->host_initiated &&
+ !guest_cpuid_has_ibpb(vcpu))
+ return 1;
+
+ if (data & ~PRED_CMD_IBPB)
+ return 1;
+
+ if (!data)
+ break;
+
+ wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB);
+ if (is_guest_mode(vcpu))
+ break;
+ set_msr_interception(svm->msrpm, MSR_IA32_PRED_CMD, 0, 1);
+ break;
+ case MSR_AMD64_VIRT_SPEC_CTRL:
+ if (!msr->host_initiated &&
+ !guest_cpuid_has_virt_ssbd(vcpu))
+ return 1;
+
+ if (data & ~SPEC_CTRL_SSBD)
+ return 1;
+
+ svm->virt_spec_ctrl = data;
+ break;
case MSR_STAR:
svm->vmcb->save.star = data;
break;
@@ -3811,6 +3930,14 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
local_irq_enable();
+ /*
+ * If this vCPU has touched SPEC_CTRL, restore the guest's value if
+ * it's non-zero. Since vmentry is serialising on affected CPUs, there
+ * is no need to worry about the conditional branch over the wrmsr
+ * being speculatively taken.
+ */
+ x86_spec_ctrl_set_guest(svm->spec_ctrl, svm->virt_spec_ctrl);
+
asm volatile (
"push %%" _ASM_BP "; \n\t"
"mov %c[rbx](%[svm]), %%" _ASM_BX " \n\t"
@@ -3915,6 +4042,26 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
#endif
#endif
+ /*
+ * We do not use IBRS in the kernel. If this vCPU has used the
+ * SPEC_CTRL MSR it may have left it on; save the value and
+ * turn it off. This is much more efficient than blindly adding
+ * it to the atomic save/restore list. Especially as the former
+ * (Saving guest MSRs on vmexit) doesn't even exist in KVM.
+ *
+ * For non-nested case:
+ * If the L01 MSR bitmap does not intercept the MSR, then we need to
+ * save it.
+ *
+ * For nested case:
+ * If the L02 MSR bitmap does not intercept the MSR, then we need to
+ * save it.
+ */
+ if (!msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL))
+ svm->spec_ctrl = native_read_msr(MSR_IA32_SPEC_CTRL);
+
+ x86_spec_ctrl_restore_host(svm->spec_ctrl, svm->virt_spec_ctrl);
+
reload_tss(vcpu);
local_irq_disable();
@@ -4015,8 +4162,15 @@ static bool svm_cpu_has_accelerated_tpr(void)
return false;
}
-static bool svm_has_high_real_mode_segbase(void)
+static bool svm_has_emulated_msr(int index)
{
+ switch (index) {
+ case MSR_IA32_MCG_EXT_CTL:
+ return false;
+ default:
+ break;
+ }
+
return true;
}
@@ -4299,7 +4453,7 @@ static struct kvm_x86_ops svm_x86_ops = {
.hardware_enable = svm_hardware_enable,
.hardware_disable = svm_hardware_disable,
.cpu_has_accelerated_tpr = svm_cpu_has_accelerated_tpr,
- .cpu_has_high_real_mode_segbase = svm_has_high_real_mode_segbase,
+ .has_emulated_msr = svm_has_emulated_msr,
.vcpu_create = svm_create_vcpu,
.vcpu_free = svm_free_vcpu,