Re: [PATCH] Add MCE support to KVM
From: Avi Kivity
Date: Thu Apr 09 2009 - 11:51:27 EST
Huang Ying wrote:
Add MCE support to KVM. The related MSRs are emulated. A new vcpu
ioctl command KVM_X86_SETUP_MCE is used to setup MCE emulation such as
the mcg_cap. MCE is injected via vcpu ioctl command
KVM_X86_SET_MCE. Extended machine-check state (MCG_EXT_P) and CMCI are
not implemented.
Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 5
arch/x86/include/asm/mce.h | 1
arch/x86/kvm/x86.c | 202 +++++++++++++++++++++++++++++++++++-----
include/linux/kvm.h | 15 ++
4 files changed, 199 insertions(+), 24 deletions(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -42,6 +42,7 @@
#include <asm/msr.h>
#include <asm/desc.h>
#include <asm/mtrr.h>
+#include <asm/mce.h>
#define MAX_IO_MSRS 256
#define CR0_RESERVED_BITS \
@@ -734,23 +735,43 @@ static int set_msr_mtrr(struct kvm_vcpu
return 0;
}
-int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
+static int set_msr_mce(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
+ u64 mcg_cap = vcpu->arch.mcg_cap;
+ unsigned bank_num = mcg_cap & 0xff;
+
switch (msr) {
- case MSR_EFER:
- set_efer(vcpu, data);
- break;
- case MSR_IA32_MC0_STATUS:
- pr_unimpl(vcpu, "%s: MSR_IA32_MC0_STATUS 0x%llx, nop\n",
- __func__, data);
- break;
case MSR_IA32_MCG_STATUS:
- pr_unimpl(vcpu, "%s: MSR_IA32_MCG_STATUS 0x%llx, nop\n",
- __func__, data);
+ vcpu->arch.mcg_status = data;
break;
case MSR_IA32_MCG_CTL:
- pr_unimpl(vcpu, "%s: MSR_IA32_MCG_CTL 0x%llx, nop\n",
- __func__, data);
+ if (!(mcg_cap & MCG_CTL_P))
+ return 1;
+ if (data != 0 && data != ~(u64)0)
+ return -1;
+ vcpu->arch.mcg_ctl = data;
+ break;
+ default:
+ if (msr >= MSR_IA32_MC0_CTL &&
+ msr < MSR_IA32_MC0_CTL + 4 * bank_num) {
+ u32 offset = msr - MSR_IA32_MC0_CTL;
+ /* only 0 or all 1s can be written to IA32_MCi_CTL */
+ if ((offset & 0x3) == 0 &&
+ data != 0 && data != ~(u64)0)
+ return -1;
+ vcpu->arch.mce_banks[offset] = data;
+ break;
+ }
+ return 1;
+ }
+ return 0;
+}
+
+int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
+{
+ switch (msr) {
+ case MSR_EFER:
+ set_efer(vcpu, data);
break;
case MSR_IA32_DEBUGCTLMSR:
if (!data) {
@@ -807,6 +828,8 @@ int kvm_set_msr_common(struct kvm_vcpu *
break;
}
default:
+ if (!set_msr_mce(vcpu, msr, data))
+ break;
pr_unimpl(vcpu, "unhandled wrmsr: 0x%x data %llx\n", msr, data);
return 1;
}
Is there any reason you split kvm_set_msr_common() into two functions?
-int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
+static int get_msr_mce(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
{
u64 data;
+ u64 mcg_cap = vcpu->arch.mcg_cap;
+ unsigned bank_num = mcg_cap & 0xff;
switch (msr) {
- case 0xc0010010: /* SYSCFG */
- case 0xc0010015: /* HWCR */
- case MSR_IA32_PLATFORM_ID:
case MSR_IA32_P5_MC_ADDR:
case MSR_IA32_P5_MC_TYPE:
- case MSR_IA32_MC0_CTL:
- case MSR_IA32_MCG_STATUS:
+ data = 0;
+ break;
case MSR_IA32_MCG_CAP:
+ data = vcpu->arch.mcg_cap;
+ break;
case MSR_IA32_MCG_CTL:
- case MSR_IA32_MC0_MISC:
- case MSR_IA32_MC0_MISC+4:
- case MSR_IA32_MC0_MISC+8:
- case MSR_IA32_MC0_MISC+12:
- case MSR_IA32_MC0_MISC+16:
- case MSR_IA32_MC0_MISC+20:
+ if (!(mcg_cap & MCG_CTL_P))
+ return 1;
+ data = vcpu->arch.mcg_ctl;
+ break;
+ case MSR_IA32_MCG_STATUS:
+ data = vcpu->arch.mcg_status;
+ break;
+ default:
+ if (msr >= MSR_IA32_MC0_CTL &&
+ msr < MSR_IA32_MC0_CTL + 4 * bank_num) {
+ u32 offset = msr - MSR_IA32_MC0_CTL;
+ data = vcpu->arch.mce_banks[offset];
+ break;
+ }
+ return 1;
+ }
+ *pdata = data;
+ return 0;
+}
+
+int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
+{
+ u64 data;
+
+ switch (msr) {
+ case 0xc0010010: /* SYSCFG */
+ case 0xc0010015: /* HWCR */
Please use MSR_ constants (add them if they don't exist yet).
+ case MSR_IA32_PLATFORM_ID:
case MSR_IA32_UCODE_REV:
case MSR_IA32_EBL_CR_POWERON:
case MSR_IA32_DEBUGCTLMSR:
@@ -921,6 +967,8 @@ int kvm_get_msr_common(struct kvm_vcpu *
data = vcpu->arch.time;
break;
default:
+ if (!get_msr_mce(vcpu, msr, &data))
+ break;
pr_unimpl(vcpu, "unhandled rdmsr: 0x%x\n", msr);
return 1;
}
@@ -1443,6 +1491,87 @@ static int vcpu_ioctl_tpr_access_reporti
return 0;
}
Again, why split?
+static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
+ u64 mcg_cap)
+{
+ int r;
+ unsigned bank_num = mcg_cap & 0xff, bank;
+ u64 *banks;
+
+ r = -EINVAL;
+ if (!bank_num)
+ goto out;
+ r = -ENOMEM;
+ banks = kzalloc(bank_num * sizeof(u64) * 4, GFP_KERNEL);
If banks is already allocated, you'll leak it.
Why not always allocate it on vcpu setup?
+static int kvm_vcpu_ioctl_x86_set_mce(struct kvm_vcpu *vcpu,
+ struct kvm_x86_mce *mce)
+{
+ u64 mcg_cap = vcpu->arch.mcg_cap;
+ unsigned bank_num = mcg_cap & 0xff;
+ u64 *banks = vcpu->arch.mce_banks;
+
+ if (mce->bank >= bank_num || !(mce->status & MCI_STATUS_VAL))
+ return -EINVAL;
+ /*
+ * if IA32_MCG_CTL is not all 1s, the uncorrected error
+ * reporting is disabled
+ */
+ if ((mce->status & MCI_STATUS_UC) && (mcg_cap & MCG_CTL_P) &&
+ vcpu->arch.mcg_ctl != ~(u64)0)
+ return 0;
+ banks += 4 * mce->bank;
+ /*
+ * if IA32_MCi_CTL is not all 1s, the uncorrected error
+ * reporting is disabled for the bank
+ */
+ if ((mce->status & MCI_STATUS_UC) && banks[0] != ~(u64)0)
+ return 0;
+ if (mce->status & MCI_STATUS_UC) {
+ u64 status = mce->status;
+ if ((vcpu->arch.mcg_status & MCG_STATUS_MCIP) ||
+ !(vcpu->arch.cr4 & X86_CR4_MCE)) {
+ printk(KERN_DEBUG "kvm: set_mce: "
+ "injects mce exception while "
+ "previous one is in progress!\n");
+ set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests);
+ return 0;
+ }
+ if (banks[1] & MCI_STATUS_VAL)
+ status |= MCI_STATUS_OVER;
+ banks[1] = mce->status;
+ banks[2] = mce->addr;
+ banks[3] = mce->misc;
+ vcpu->arch.mcg_status = mce->mcg_status;
+ kvm_queue_exception(vcpu, MC_VECTOR);
+ } else if (!(banks[1] & MCI_STATUS_VAL) ||
+ (!(banks[1] & MCI_STATUS_UC) &&
+ !((mcg_cap & MCG_TES_P) && ((banks[1]>>53) & 0x3) < 2))) {
+ u64 status = mce->status;
+ if (banks[1] & MCI_STATUS_VAL)
+ status |= MCI_STATUS_OVER;
+ banks[1] = mce->status;
+ banks[2] = mce->addr;
+ banks[3] = mce->misc;
+ } else
+ banks[1] |= MCI_STATUS_OVER;
+ return 0;
+}
Can userspace just use KVM_SET_MSR for this?
+ case KVM_X86_SETUP_MCE: {
+ u64 mcg_cap;
+
+ r = -EFAULT;
+ if (copy_from_user(&mcg_cap, argp, sizeof mcg_cap))
+ goto out;
+ /*
+ * extended machine-check state registers and CMCI are
+ * not supported.
+ */
+ mcg_cap &= ~(MCG_EXT_P|MCG_CMCI_P);
Instead of silently dropping, should return an error.
+ if (copy_to_user(argp, &mcg_cap, sizeof mcg_cap))
+ goto out;
And not copy.
#define KVM_TRC_SHIFT 16
/*
* kvm trace categories
@@ -528,6 +540,9 @@ struct kvm_irq_routing {
#define KVM_NMI _IO(KVMIO, 0x9a)
/* Available with KVM_CAP_SET_GUEST_DEBUG */
#define KVM_SET_GUEST_DEBUG _IOW(KVMIO, 0x9b, struct kvm_guest_debug)
+/* MCE for x86 */
+#define KVM_X86_SETUP_MCE _IOWR(KVMIO, 0x9a, __u64)
+#define KVM_X86_SET_MCE _IOW(KVMIO, 0x9b, struct kvm_x86_mce)
Please add a KVM_CAP_ to advertise this capability.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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