[v19,099/130] KVM: TDX: Handle vmentry failure for INTEL TD guest

Message ID f4fff979b347302c88a114efccb616a9895860f5.1708933498.git.isaku.yamahata@intel.com
State New
Headers
Series [v19,001/130] x86/virt/tdx: Rename _offset to _member for TD_SYSINFO_MAP() macro |

Commit Message

Isaku Yamahata Feb. 26, 2024, 8:26 a.m. UTC
  From: Yao Yuan <yuan.yao@intel.com>

TDX module passes control back to VMM if it failed to vmentry for a TD, use
same exit reason to notify user space, align with VMX.
If VMM corrupted TD VMCS, machine check during entry can happens.  vm exit
reason will be EXIT_REASON_MCE_DURING_VMENTRY.  If VMM corrupted TD VMCS
with debug TD by TDH.VP.WR, the exit reason would be
EXIT_REASON_INVALID_STATE or EXIT_REASON_MSR_LOAD_FAIL.

Signed-off-by: Yao Yuan <yuan.yao@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
 arch/x86/kvm/vmx/tdx.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
  

Patch

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 71ab48cf72ba..cba0fd5029be 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1320,6 +1320,28 @@  int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
 		goto unhandled_exit;
 	}
 
+	/*
+	 * When TDX module saw VMEXIT_REASON_FAILED_VMENTER_MC etc, TDH.VP.ENTER
+	 * returns with TDX_SUCCESS | exit_reason with failed_vmentry = 1.
+	 * Because TDX module maintains TD VMCS correctness, usually vmentry
+	 * failure shouldn't happen.  In some corner cases it can happen.  For
+	 * example
+	 * - machine check during entry: EXIT_REASON_MCE_DURING_VMENTRY
+	 * - TDH.VP.WR with debug TD.  VMM can corrupt TD VMCS
+	 *   - EXIT_REASON_INVALID_STATE
+	 *   - EXIT_REASON_MSR_LOAD_FAIL
+	 */
+	if (unlikely(exit_reason.failed_vmentry)) {
+		pr_err("TDExit: exit_reason 0x%016llx qualification=%016lx ext_qualification=%016lx\n",
+		       exit_reason.full, tdexit_exit_qual(vcpu), tdexit_ext_exit_qual(vcpu));
+		vcpu->run->exit_reason = KVM_EXIT_FAIL_ENTRY;
+		vcpu->run->fail_entry.hardware_entry_failure_reason
+			= exit_reason.full;
+		vcpu->run->fail_entry.cpu = vcpu->arch.last_vmentry_cpu;
+
+		return 0;
+	}
+
 	WARN_ON_ONCE(fastpath != EXIT_FASTPATH_NONE);
 
 	switch (exit_reason.basic) {