Messages in this thread | | | Subject | Re: [PATCH v2 7/9] KVM: x86/xen: Drop RAX[63:32] when processing hypercall | From | Paolo Bonzini <> | Date | Thu, 22 Apr 2021 12:35:06 +0200 |
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On 22/04/21 11:51, Vitaly Kuznetsov wrote: > Sean Christopherson <seanjc@google.com> 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@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) && > > Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> > > 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
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