Commit 6b48fd4c authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/xen: Drop RAX[63:32] when processing hypercall 

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: 23200b7a ("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: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210422022128.3464144-8-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 82277eee

arch/x86/kvm/xen.c

+1 −1
Original line number Diff line number Diff line
@@ -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) &&