linux-kernel - [PATCH 8/9] KVM: SVM: Use default rAX size for INVLPGA emulation

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Message-Id: <20210213010518.1682691-9-seanjc@google.com>
Date:   Fri, 12 Feb 2021 17:05:17 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Babu Moger <babu.moger@....com>,
        Joao Martins <joao.m.martins@...cle.com>,
        David Woodhouse <dwmw@...zon.co.uk>
Subject: [PATCH 8/9] KVM: SVM: Use default rAX size for INVLPGA emulation

Drop bits 63:32 of RAX when grabbing the address for INVLPGA emulation
outside of 64-bit mode to make KVM's emulation slightly less wrong.  The
address for INVLPGA is determined by the effective address size, i.e.
it's not hardcoded to 64/32 bits for a given mode.  Add a FIXME to call
out that the emulation is wrong.

Opportunistically tweak the ASID handling to make it clear that it's
defined by ECX, not rCX.

Per the APM:
   The portion of rAX used to form the address is determined by the
   effective address size (current execution mode and optional address
   size prefix). The ASID is taken from ECX.

Fixes: ff092385e828 ("KVM: SVM: Implement INVLPGA")
Cc: stable@...r.kernel.org
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index d077584d45ec..4dc64ebaa756 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2327,12 +2327,17 @@ static int clgi_interception(struct vcpu_svm *svm)
 static int invlpga_interception(struct vcpu_svm *svm)
 {
 	struct kvm_vcpu *vcpu = &svm->vcpu;
+	gva_t gva = kvm_rax_read(vcpu);
+	u32 asid = kvm_rcx_read(vcpu);
 
-	trace_kvm_invlpga(svm->vmcb->save.rip, kvm_rcx_read(&svm->vcpu),
-			  kvm_rax_read(&svm->vcpu));
+	/* FIXME: Handle an address size prefix. */
+	if (!is_long_mode(vcpu))
+		gva = (u32)gva;
+
+	trace_kvm_invlpga(svm->vmcb->save.rip, asid, gva);
 
 	/* Let's treat INVLPGA the same as INVLPG (can be optimized!) */
-	kvm_mmu_invlpg(vcpu, kvm_rax_read(&svm->vcpu));
+	kvm_mmu_invlpg(vcpu, gva);
 
 	return kvm_skip_emulated_instruction(&svm->vcpu);
 }
-- 
2.30.0.478.g8a0d178c01-goog