[PATCH 6/6] KVM: VMX: Add instruction rdtscp support for guest

Sheng Yang
2009-12-18T08:48:59Z

Before enabling, execution of "rdtscp" in guest would result in #UD.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/include/asm/vmx.h | 1 +
arch/x86/kvm/svm.c | 7 ++++
arch/x86/kvm/vmx.c | 60 +++++++++++++++++++++++++++++++++++++--
arch/x86/kvm/x86.c | 3 +-
5 files changed, 68 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index d2a91ae..07e6636 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -533,6 +533,7 @@ struct kvm_x86_ops {
int (*get_tdp_level)(void);
u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
bool (*gb_page_enable)(void);
+ bool (*rdtscp_supported)(void);

const struct trace_print_flags *exit_reasons_str;
};
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 2b49454..8c39320 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -53,6 +53,7 @@
*/
#define SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES 0x00000001
#define SECONDARY_EXEC_ENABLE_EPT 0x00000002
+#define SECONDARY_EXEC_RDTSCP 0x00000008
#define SECONDARY_EXEC_ENABLE_VPID 0x00000020
#define SECONDARY_EXEC_WBINVD_EXITING 0x00000040
#define SECONDARY_EXEC_UNRESTRICTED_GUEST 0x00000080
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index d89b0a0..3a880ac 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2916,6 +2916,11 @@ static bool svm_gb_page_enable(void)
return true;
}

+static bool svm_rdtscp_supported(void)
+{
+ return false;
+}
+
static struct kvm_x86_ops svm_x86_ops = {
.cpu_has_kvm_support = has_svm,
.disabled_by_bios = is_disabled,
@@ -2984,6 +2989,8 @@ static struct kvm_x86_ops svm_x86_ops = {
.gb_page_enable = svm_gb_page_enable,

.cpuid_update = svm_cpuid_update,
+
+ .rdtscp_supported = svm_rdtscp_supported,
};

static int __init svm_init(void)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 91dff23..584403f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -136,6 +136,8 @@ struct vcpu_vmx {
ktime_t entry_time;
s64 vnmi_blocked_time;
u32 exit_reason;
+
+ bool rdtscp_enabled;
};

static inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu)
@@ -210,7 +212,7 @@ static const u32 vmx_msr_index[] = {
#ifdef CONFIG_X86_64
MSR_SYSCALL_MASK, MSR_LSTAR, MSR_CSTAR,
#endif
- MSR_EFER, MSR_K6_STAR,
+ MSR_EFER, MSR_TSC_AUX, MSR_K6_STAR,
};
#define NR_VMX_MSR ARRAY_SIZE(vmx_msr_index)

@@ -347,6 +349,12 @@ static inline int cpu_has_vmx_vpid(void)
SECONDARY_EXEC_ENABLE_VPID;
}

+static inline int cpu_has_vmx_rdtscp(void)
+{
+ return vmcs_config.cpu_based_2nd_exec_ctrl &
+ SECONDARY_EXEC_RDTSCP;
+}
+
static inline int cpu_has_virtual_nmis(void)
{
return vmcs_config.pin_based_exec_ctrl & PIN_BASED_VIRTUAL_NMIS;
@@ -878,6 +886,11 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu, unsigned nr,
vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info);
}

+static bool vmx_rdtscp_supported(void)
+{
+ return cpu_has_vmx_rdtscp();
+}
+
/*
* Swap MSR entry in host/guest MSR entry array.
*/
@@ -913,6 +926,9 @@ static void setup_msrs(struct vcpu_vmx *vmx)
index = __find_msr_index(vmx, MSR_CSTAR);
if (index >= 0)
move_msr_up(vmx, index, save_nmsrs++);
+ index = __find_msr_index(vmx, MSR_TSC_AUX);
+ if (index >= 0 && vmx->rdtscp_enabled)
+ move_msr_up(vmx, index, save_nmsrs++);
/*
* MSR_K6_STAR is only needed on long mode guests, and only
* if efer.sce is enabled.
@@ -1002,6 +1018,10 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
case MSR_IA32_SYSENTER_ESP:
data = vmcs_readl(GUEST_SYSENTER_ESP);
break;
+ case MSR_TSC_AUX:
+ if (!to_vmx(vcpu)->rdtscp_enabled)
+ return 1;
+ /* Otherwise falls through */
default:
vmx_load_host_state(to_vmx(vcpu));
msr = find_msr_entry(to_vmx(vcpu), msr_index);
@@ -1065,7 +1085,15 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
vcpu->arch.pat = data;
break;
}
- /* Otherwise falls through to kvm_set_msr_common */
+ ret = kvm_set_msr_common(vcpu, msr_index, data);
+ break;
+ case MSR_TSC_AUX:
+ if (!vmx->rdtscp_enabled)
+ return 1;
+ /* Check reserved bit, higher 32 bits should be zero */
+ if ((data >> 32) != 0)
+ return 1;
+ /* Otherwise falls through */
default:
msr = find_msr_entry(vmx, msr_index);
if (msr) {
@@ -1243,7 +1271,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf)
SECONDARY_EXEC_ENABLE_VPID |
SECONDARY_EXEC_ENABLE_EPT |
SECONDARY_EXEC_UNRESTRICTED_GUEST |
- SECONDARY_EXEC_PAUSE_LOOP_EXITING;
+ SECONDARY_EXEC_PAUSE_LOOP_EXITING |
+ SECONDARY_EXEC_RDTSCP;
if (adjust_vmx_controls(min2, opt2,
MSR_IA32_VMX_PROCBASED_CTLS2,
&_cpu_based_2nd_exec_control) < 0)
@@ -3961,8 +3990,31 @@ static bool vmx_gb_page_enable(void)
return false;
}

+static inline u32 bit(int bitno)
+{
+ return 1 << (bitno & 31);
+}
+
static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
{
+ struct kvm_cpuid_entry2 *best;
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ u32 exec_control;
+
+ vmx->rdtscp_enabled = false;
+ if (vmx_rdtscp_supported()) {
+ exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
+ if (exec_control & SECONDARY_EXEC_RDTSCP) {
+ best = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
+ if (best && (best->edx & bit(X86_FEATURE_RDTSCP)))
+ vmx->rdtscp_enabled = true;
+ else {
+ exec_control &= ~SECONDARY_EXEC_RDTSCP;
+ vmcs_write32(SECONDARY_VM_EXEC_CONTROL,
+ exec_control);
+ }
+ }
+ }
}

static struct kvm_x86_ops vmx_x86_ops = {
@@ -4031,6 +4083,8 @@ static struct kvm_x86_ops vmx_x86_ops = {
.gb_page_enable = vmx_gb_page_enable,

.cpuid_update = vmx_cpuid_update,
+
+ .rdtscp_supported = vmx_rdtscp_supported,
};

static int __init vmx_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e16dede..91e4234 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1646,6 +1646,7 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
#else
unsigned f_lm = 0;
#endif
+ unsigned f_rdtscp = kvm_x86_ops->rdtscp_supported() ? F(RDTSCP) : 0;

/* cpuid 1.edx */
const u32 kvm_supported_word0_x86_features =
@@ -1665,7 +1666,7 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
F(PAT) | F(PSE36) | 0 /* Reserved */ |
f_nx | 0 /* Reserved */ | F(MMXEXT) | F(MMX) |
- F(FXSR) | F(FXSR_OPT) | f_gbpages | 0 /* RDTSCP */ |
+ F(FXSR) | F(FXSR_OPT) | f_gbpages | f_rdtscp |
0 /* Reserved */ | f_lm | F(3DNOWEXT) | F(3DNOW);
/* cpuid 1.ecx */
const u32 kvm_supported_word4_x86_features =
--
1.5.4.5