[RFC PATCH v3 17/59] KVM: x86: Add flag to disallow #MC injection / KVM_X86_SETUP_MCE

isaku.yamahata
2021-11-25T00:25:14Z

From: Sean Christopherson <sean.j.christopherson@intel.com>

Add a flag to disallow MCE injection and reject KVM_X86_SETUP_MCE with
-EINVAL when set. TDX doesn't support injecting exceptions, including
(virtual) #MCs.

Co-developed-by: Kai Huang <kai.huang@linux.intel.com>
Signed-off-by: Kai Huang <kai.huang@linux.intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/x86.c | 14 +++++++-------
2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index ebc4de32bf0e..e912e1e853ef 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1142,6 +1142,7 @@ struct kvm_arch {

bool bus_lock_detection_enabled;
bool irq_injection_disallowed;
+ bool mce_injection_disallowed;
/*
* If exit_on_emulation_error is set, and the in-kernel instruction
* emulator fails to emulate an instruction, allow userspace
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b399e64e8863..fefa4602e879 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4561,15 +4561,16 @@ static int vcpu_ioctl_tpr_access_reporting(struct kvm_vcpu *vcpu,
static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
u64 mcg_cap)
{
- int r;
unsigned bank_num = mcg_cap & 0xff, bank;

- r = -EINVAL;
+ if (vcpu->kvm->arch.mce_injection_disallowed)
+ return -EINVAL;
+
if (!bank_num || bank_num > KVM_MAX_MCE_BANKS)
- goto out;
+ return -EINVAL;
if (mcg_cap & ~(kvm_mce_cap_supported | 0xff | 0xff0000))
- goto out;
- r = 0;
+ return -EINVAL;
+
vcpu->arch.mcg_cap = mcg_cap;
/* Init IA32_MCG_CTL to all 1s */
if (mcg_cap & MCG_CTL_P)
@@ -4579,8 +4580,7 @@ static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
vcpu->arch.mce_banks[bank*4] = ~(u64)0;

static_call(kvm_x86_setup_mce)(vcpu);
-out:
- return r;
+ return 0;
}

static int kvm_vcpu_ioctl_x86_set_mce(struct kvm_vcpu *vcpu,
--
2.25.1