On 22/04/21 11:51, Vitaly Kuznetsov wrote:
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);
You haven't seen patch 9 yet. :)
Paolo
