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From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Babu Moger <babu.moger@amd.com>,
	Joao Martins <joao.m.martins@oracle.com>,
	David Woodhouse <dwmw@amazon.co.uk>
Subject: [PATCH v2 7/9] KVM: x86/xen: Drop RAX[63:32] when processing hypercall
Date: Wed, 21 Apr 2021 19:21:26 -0700	[thread overview]
Message-ID: <20210422022128.3464144-8-seanjc@google.com> (raw)
In-Reply-To: <20210422022128.3464144-1-seanjc@google.com>

Truncate RAX to 32 bits, i.e. consume EAX, when retrieving the hypecall
index for a Xen hypercall.  Per Xen documentation[*], the index is EAX
when the vCPU is not in 64-bit mode.

[*] http://xenbits.xenproject.org/docs/sphinx-unstable/guest-guide/x86/hypercall-abi.html

Fixes: 23200b7a30de ("KVM: x86/xen: intercept xen hypercalls if enabled")
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/xen.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index ae17250e1efe..7f27bb65a572 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -673,7 +673,7 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
 	bool longmode;
 	u64 input, params[6];
 
-	input = (u64)kvm_register_read(vcpu, VCPU_REGS_RAX);
+	input = (u64)kvm_register_readl(vcpu, VCPU_REGS_RAX);
 
 	/* Hyper-V hypercalls get bit 31 set in EAX */
 	if ((input & 0x80000000) &&
-- 
2.31.1.498.g6c1eba8ee3d-goog


  parent reply	other threads:[~2021-04-22  2:21 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-22  2:21 [PATCH v2 0/9] KVM: x86: Fixes for (benign?) truncation bugs Sean Christopherson
2021-04-22  2:21 ` [PATCH v2 1/9] KVM: x86: Remove emulator's broken checks on CR0/CR3/CR4 loads Sean Christopherson
2021-04-22  6:50   ` Paolo Bonzini
2021-04-22  2:21 ` [PATCH v2 2/9] KVM: x86: Check CR3 GPA for validity regardless of vCPU mode Sean Christopherson
2021-04-22  6:51   ` Paolo Bonzini
2021-04-22 16:55     ` Sean Christopherson
2021-04-22  2:21 ` [PATCH v2 3/9] KVM: SVM: Truncate GPR value for DR and CR accesses in !64-bit mode Sean Christopherson
2021-04-22  2:21 ` [PATCH v2 4/9] KVM: VMX: Truncate GPR value for DR and CR reads " Sean Christopherson
2021-04-22  2:21 ` [PATCH v2 5/9] KVM: nVMX: Truncate bits 63:32 of VMCS field on nested check in !64-bit Sean Christopherson
2021-04-22  2:21 ` [PATCH v2 6/9] KVM: nVMX: Truncate base/index GPR value on address calc " Sean Christopherson
2021-04-22  2:21 ` Sean Christopherson [this message]
2021-04-22  9:51   ` [PATCH v2 7/9] KVM: x86/xen: Drop RAX[63:32] when processing hypercall Vitaly Kuznetsov
2021-04-22 10:35     ` Paolo Bonzini
2021-04-22 10:49       ` Vitaly Kuznetsov
2021-04-22  2:21 ` [PATCH v2 8/9] KVM: SVM: Use default rAX size for INVLPGA emulation Sean Christopherson
2021-04-22  2:21 ` [PATCH v2 9/9] KVM: x86: Rename GPR accessors to make mode-aware variants the defaults Sean Christopherson
2021-04-22  6:55 ` [PATCH v2 0/9] KVM: x86: Fixes for (benign?) truncation bugs Paolo Bonzini

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