Sean Christopherson <seanjc@xxxxxxxxxx> writes: > 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@xxxxxxxxxx> > Cc: David Woodhouse <dwmw@xxxxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> > --- > 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) && Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Alternatively, as a minor optimization, you could've used '!longmode' check below, something like: diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index ae17250e1efe..7df1498d3a41 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -682,6 +682,7 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu) longmode = is_64_bit_mode(vcpu); if (!longmode) { + input = (u32)input; params[0] = (u32)kvm_rbx_read(vcpu); params[1] = (u32)kvm_rcx_read(vcpu); params[2] = (u32)kvm_rdx_read(vcpu); -- Vitaly
