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Message-Id: <93afacf52041d9a418a27b05f31031cf7676aa3f.1673539699.git.isaku.yamahata@intel.com>
Date: Thu, 12 Jan 2023 08:32:33 -0800
From: isaku.yamahata@...el.com
To: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: isaku.yamahata@...el.com, isaku.yamahata@...il.com,
Paolo Bonzini <pbonzini@...hat.com>, erdemaktas@...gle.com,
Sean Christopherson <seanjc@...gle.com>,
Sagi Shahar <sagis@...gle.com>,
David Matlack <dmatlack@...gle.com>,
Yao Yuan <yuan.yao@...el.com>
Subject: [PATCH v11 085/113] KVM: TDX: Handle vmentry failure for INTEL TD guest
From: Yao Yuan <yuan.yao@...el.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@...el.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
---
arch/x86/kvm/vmx/tdx.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 964154f7bc60..47ea12f23471 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1094,6 +1094,28 @@ 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) {
--
2.25.1
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