[PATCH v5 7/8] KVM: x86: Enable CMCI capability by default and handle injected UCNA errors

Jue Wang
2022-06-10T17:12:07Z

This patch enables MCG_CMCI_P by default in kvm_mce_cap_supported. It
reuses ioctl KVM_X86_SET_MCE to implement injection of UnCorrectable
No Action required (UCNA) errors, signaled via Corrected Machine
Check Interrupt (CMCI).

Neither of the CMCI and UCNA emulations depends on hardware.

Signed-off-by: Jue Wang <juew@google.com>
---
arch/x86/kvm/vmx/vmx.c | 1 +
arch/x86/kvm/x86.c | 44 +++++++++++++++++++++++++++++++++++++++++-
2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 610355b9ccce..1aed964ee4ee 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -8037,6 +8037,7 @@ static __init int hardware_setup(void)
}

kvm_mce_cap_supported |= MCG_LMCE_P;
+ kvm_mce_cap_supported |= MCG_CMCI_P;

if (pt_mode != PT_MODE_SYSTEM && pt_mode != PT_MODE_HOST_GUEST)
return -EINVAL;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b18994907322..4322a1365f74 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4828,6 +4828,43 @@ static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
return r;
}

+/*
+ * Validate this is an UCNA error by checking the MCG_STATUS and MCi_STATUS
+ * registers that none of the bits for Machine Check Exceptions are set and
+ * both the VAL (valid) and UC (uncorrectable) bits are set.
+ * UCNA - UnCorrectable No Action required
+ * SRAR - Software Recoverable Action Required
+ * MCI_STATUS_PCC - Processor Context Corrupted
+ * MCI_STATUS_S - Signaled as a Machine Check Exception
+ * MCI_STATUS_AR - This MCE is "software recoverable action required"
+ */
+static bool is_ucna(struct kvm_x86_mce *mce)
+{
+ return !mce->mcg_status &&
+ !(mce->status & (MCI_STATUS_PCC | MCI_STATUS_S | MCI_STATUS_AR)) &&
+ (mce->status & MCI_STATUS_VAL) &&
+ (mce->status & MCI_STATUS_UC);
+}
+
+static int kvm_vcpu_x86_set_ucna(struct kvm_vcpu *vcpu, struct kvm_x86_mce *mce, u64* banks)
+{
+ u64 mcg_cap = vcpu->arch.mcg_cap;
+
+ banks[1] = mce->status;
+ banks[2] = mce->addr;
+ banks[3] = mce->misc;
+ vcpu->arch.mcg_status = mce->mcg_status;
+
+ if (!(mcg_cap & MCG_CMCI_P) ||
+ !(vcpu->arch.mci_ctl2_banks[mce->bank] & MCI_CTL2_CMCI_EN))
+ return 0;
+
+ if (lapic_in_kernel(vcpu))
+ kvm_apic_local_deliver(vcpu->arch.apic, APIC_LVTCMCI);
+
+ return 0;
+}
+
static int kvm_vcpu_ioctl_x86_set_mce(struct kvm_vcpu *vcpu,
struct kvm_x86_mce *mce)
{
@@ -4837,6 +4874,12 @@ static int kvm_vcpu_ioctl_x86_set_mce(struct kvm_vcpu *vcpu,

if (mce->bank >= bank_num || !(mce->status & MCI_STATUS_VAL))
return -EINVAL;
+
+ banks += array_index_nospec(4 * mce->bank, 4 * bank_num);
+
+ if (is_ucna(mce))
+ return kvm_vcpu_x86_set_ucna(vcpu, mce, banks);
+
/*
* if IA32_MCG_CTL is not all 1s, the uncorrected error
* reporting is disabled
@@ -4844,7 +4887,6 @@ static int kvm_vcpu_ioctl_x86_set_mce(struct kvm_vcpu *vcpu,
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
--
2.36.1.255.ge46751e96f-goog