linux-kernel - [RFC PATCH 09/35] KVM: SVM: Do not emulate MMIO under SEV-ES

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Message-Id: <c4ccb48b41f3996bc9000730309455e449cb1136.1600114548.git.thomas.lendacky@amd.com>
Date:   Mon, 14 Sep 2020 15:15:23 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Brijesh Singh <brijesh.singh@....com>
Subject: [RFC PATCH 09/35] KVM: SVM: Do not emulate MMIO under SEV-ES

From: Tom Lendacky <thomas.lendacky@....com>

When a guest is running as an SEV-ES guest, it is not possible to emulate
MMIO. Add support to prevent trying to perform MMIO emulation.

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kvm/mmu/mmu.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index a5d0207e7189..2e1b8b876286 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5485,6 +5485,13 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
 	if (!mmio_info_in_cache(vcpu, cr2_or_gpa, direct) && !is_guest_mode(vcpu))
 		emulation_type |= EMULTYPE_ALLOW_RETRY_PF;
 emulate:
+	/*
+	 * When the guest is an SEV-ES guest, emulation is not possible.  Allow
+	 * the guest to handle the MMIO emulation.
+	 */
+	if (vcpu->arch.vmsa_encrypted)
+		return 1;
+
 	/*
 	 * On AMD platforms, under certain conditions insn_len may be zero on #NPF.
 	 * This can happen if a guest gets a page-fault on data access but the HW
-- 
2.28.0