[PATCH v2 3/3] KVM: VMX: enable guest access to LMCE related MSRs

Haozhong Zhang
2016-06-16T06:05:31Z

From: Ashok Raj <ashok.raj@intel.com>

On Intel platforms, this patch adds LMCE to KVM MCE supported
capabilities and handles guest access to LMCE related MSRs.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
[Haozhong: macro KVM_MCE_CAP_SUPPORTED => variable kvm_mce_cap_supported
Only enable LMCE on Intel platform
Check MSR_IA32_FEATURE_CONTROL when handling guest
access to MSR_IA32_MCG_EXT_CTL]
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
---
arch/x86/include/asm/kvm_host.h | 5 +++++
arch/x86/kvm/vmx.c | 36 +++++++++++++++++++++++++++++++++++-
arch/x86/kvm/x86.c | 15 +++++++++------
3 files changed, 49 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e0fbe7e..75defa6 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -598,6 +598,7 @@ struct kvm_vcpu_arch {
u64 mcg_cap;
u64 mcg_status;
u64 mcg_ctl;
+ u64 mcg_ext_ctl;
u64 *mce_banks;

/* Cache MMIO info */
@@ -1005,6 +1006,8 @@ struct kvm_x86_ops {
int (*update_pi_irte)(struct kvm *kvm, unsigned int host_irq,
uint32_t guest_irq, bool set);
void (*apicv_post_state_restore)(struct kvm_vcpu *vcpu);
+
+ void (*setup_mce)(struct kvm_vcpu *vcpu);
};

struct kvm_arch_async_pf {
@@ -1077,6 +1080,8 @@ extern u8 kvm_tsc_scaling_ratio_frac_bits;
/* maximum allowed value of TSC scaling ratio */
extern u64 kvm_max_tsc_scaling_ratio;

+extern u64 kvm_mce_cap_supported;
+
enum emulation_result {
EMULATE_DONE, /* no further processing */
EMULATE_USER_EXIT, /* kvm_run ready for userspace exit */
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1dc89c5..42db42e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -638,7 +638,7 @@ static struct pi_desc *vcpu_to_pi_desc(struct kvm_vcpu *vcpu)
* feature_control_valid_bits_add/del(), so it's not included here.
*/
#define FEATURE_CONTROL_MAX_VALID_BITS \
- FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX
+ (FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX | FEATURE_CONTROL_LMCE)

static void feature_control_valid_bits_add(struct kvm_vcpu *vcpu, uint64_t bits)
{
@@ -2905,6 +2905,15 @@ static inline bool vmx_feature_control_msr_valid(struct kvm_vcpu *vcpu,
return valid_bits && !(val & ~valid_bits);
}

+static inline bool vmx_mcg_ext_ctrl_msr_present(struct kvm_vcpu *vcpu,
+ bool host_initiated)
+{
+ return (vcpu->arch.mcg_cap & MCG_LMCE_P) &&
+ (host_initiated ||
+ (to_vmx(vcpu)->msr_ia32_feature_control &
+ FEATURE_CONTROL_LMCE));
+}
+
/*
* Reads an msr value (of 'msr_index') into 'pdata'.
* Returns 0 on success, non-0 otherwise.
@@ -2946,6 +2955,12 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
return 1;
msr_info->data = vmcs_read64(GUEST_BNDCFGS);
break;
+ case MSR_IA32_MCG_EXT_CTL:
+ if (!vmx_mcg_ext_ctrl_msr_present(vcpu,
+ msr_info->host_initiated))
+ return 1;
+ msr_info->data = vcpu->arch.mcg_ext_ctl;
+ break;
case MSR_IA32_FEATURE_CONTROL:
if (!vmx_feature_control_msr_valid(vcpu, 0))
return 1;
@@ -3039,6 +3054,13 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_IA32_TSC_ADJUST:
ret = kvm_set_msr_common(vcpu, msr_info);
break;
+ case MSR_IA32_MCG_EXT_CTL:
+ if (!vmx_mcg_ext_ctrl_msr_present(vcpu,
+ msr_info->host_initiated) ||
+ (data & ~MCG_EXT_CTL_LMCE_EN))
+ return 1;
+ vcpu->arch.mcg_ext_ctl = data;
+ break;
case MSR_IA32_FEATURE_CONTROL:
if (!vmx_feature_control_msr_valid(vcpu, data) ||
(to_vmx(vcpu)->msr_ia32_feature_control &
@@ -6433,6 +6455,8 @@ static __init int hardware_setup(void)

kvm_set_posted_intr_wakeup_handler(wakeup_handler);

+ kvm_mce_cap_supported |= MCG_LMCE_P;
+
return alloc_kvm_area();

out8:
@@ -10950,6 +10974,14 @@ out:
return ret;
}

+static void vmx_setup_mce(struct kvm_vcpu *vcpu)
+{
+ if (vcpu->arch.mcg_cap & MCG_LMCE_P)
+ feature_control_valid_bits_add(vcpu, FEATURE_CONTROL_LMCE);
+ else
+ feature_control_valid_bits_del(vcpu, FEATURE_CONTROL_LMCE);
+}
+
static struct kvm_x86_ops vmx_x86_ops = {
.cpu_has_kvm_support = cpu_has_kvm_support,
.disabled_by_bios = vmx_disabled_by_bios,
@@ -11074,6 +11106,8 @@ static struct kvm_x86_ops vmx_x86_ops = {
.pmu_ops = &intel_pmu_ops,

.update_pi_irte = vmx_update_pi_irte,
+
+ .setup_mce = vmx_setup_mce,
};

static int __init vmx_init(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bf22721..5bf76ab 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -70,7 +70,8 @@

#define MAX_IO_MSRS 256
#define KVM_MAX_MCE_BANKS 32
-#define KVM_MCE_CAP_SUPPORTED (MCG_CTL_P | MCG_SER_P)
+u64 __read_mostly kvm_mce_cap_supported = MCG_CTL_P | MCG_SER_P;
+EXPORT_SYMBOL_GPL(kvm_mce_cap_supported);

#define emul_to_vcpu(ctxt) \
container_of(ctxt, struct kvm_vcpu, arch.emulate_ctxt)
@@ -983,6 +984,7 @@ static u32 emulated_msrs[] = {
MSR_IA32_MISC_ENABLE,
MSR_IA32_MCG_STATUS,
MSR_IA32_MCG_CTL,
+ MSR_IA32_MCG_EXT_CTL,
MSR_IA32_SMBASE,
};

@@ -2684,11 +2686,9 @@ long kvm_arch_dev_ioctl(struct file *filp,
break;
}
case KVM_X86_GET_MCE_CAP_SUPPORTED: {
- u64 mce_cap;
-
- mce_cap = KVM_MCE_CAP_SUPPORTED;
r = -EFAULT;
- if (copy_to_user(argp, &mce_cap, sizeof mce_cap))
+ if (copy_to_user(argp, &kvm_mce_cap_supported,
+ sizeof(kvm_mce_cap_supported)))
goto out;
r = 0;
break;
@@ -2866,7 +2866,7 @@ static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
r = -EINVAL;
if (!bank_num || bank_num >= KVM_MAX_MCE_BANKS)
goto out;
- if (mcg_cap & ~(KVM_MCE_CAP_SUPPORTED | 0xff | 0xff0000))
+ if (mcg_cap & ~(kvm_mce_cap_supported | 0xff | 0xff0000))
goto out;
r = 0;
vcpu->arch.mcg_cap = mcg_cap;
@@ -2876,6 +2876,9 @@ static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
/* Init IA32_MCi_CTL to all 1s */
for (bank = 0; bank < bank_num; bank++)
vcpu->arch.mce_banks[bank*4] = ~(u64)0;
+
+ if (kvm_x86_ops->setup_mce)
+ kvm_x86_ops->setup_mce(vcpu);
out:
return r;
}
--
2.9.0