linux-kernel - [PATCH] KVM: VMX: Resume guest immediately when injecting #GP on ECREATE

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Message-ID: <20220930233132.1723330-1-seanjc@google.com>
Date:   Fri, 30 Sep 2022 23:31:32 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kai Huang <kai.huang@...el.com>
Subject: [PATCH] KVM: VMX: Resume guest immediately when injecting #GP on ECREATE

Resume the guest immediately when injecting a #GP on ECREATE due to an
invalid enclave size, i.e. don't attempt ECREATE in the host.  The #GP is
a terminal fault, e.g. skipping the instruction if ECREATE is successful
would result in KVM injecting #GP on the instruction following ECREATE.

Fixes: 70210c044b4e ("KVM: VMX: Add SGX ENCLS[ECREATE] handler to enforce CPUID restrictions")
Cc: stable@...r.kernel.org
Cc: Kai Huang <kai.huang@...el.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---

Effectively compile tested only, found by inspection when auditing use of
kvm_skip_emulated_instruction().

 arch/x86/kvm/vmx/sgx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/sgx.c b/arch/x86/kvm/vmx/sgx.c
index 8f95c7c01433..b12da2a6dec9 100644
--- a/arch/x86/kvm/vmx/sgx.c
+++ b/arch/x86/kvm/vmx/sgx.c
@@ -182,8 +182,10 @@ static int __handle_encls_ecreate(struct kvm_vcpu *vcpu,
 	/* Enforce CPUID restriction on max enclave size. */
 	max_size_log2 = (attributes & SGX_ATTR_MODE64BIT) ? sgx_12_0->edx >> 8 :
 							    sgx_12_0->edx;
-	if (size >= BIT_ULL(max_size_log2))
+	if (size >= BIT_ULL(max_size_log2)) {
 		kvm_inject_gp(vcpu, 0);
+		return 1;
+	}
 
 	/*
 	 * sgx_virt_ecreate() returns:

base-commit: c59fb127583869350256656b7ed848c398bef879
-- 
2.38.0.rc1.362.ged0d419d3c-goog