Re: [PATCH v15 21/23] KVM: selftests: Add support for per-VM ucall ops on x86

[Binbin Wu <binbin.wu@linux.intel.com>]

On 10/2/2026 3:37 AM, Lisa Wang wrote:
> From: Sean Christopherson <seanjc@google.com>
> 
> Add a layer of indirection to x86's ucall infrastructure to allow wiring up
> a different set of {do,get}_ucall() operations for TDX VMs.  TDX can't use
> port I/O (at least, not robustly), as the TDX ABI doesn't allow the guest
> to share arbitrary register state with the host on a PIO exit, and the PIO
> data payload is limited to 4 bytes, i.e. would potentially truncate the
> address of the per-ucall structure.
> 
> No functional change intended, as the ops are still hardwired to the common
> x86 ucall functions.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Lisa Wang <wyihan@google.com>
> ---
>  tools/testing/selftests/kvm/include/x86/ucall.h |  6 +-----
>  tools/testing/selftests/kvm/lib/x86/ucall.c     | 27 +++++++++++++++++++++++--
>  2 files changed, 26 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/include/x86/ucall.h b/tools/testing/selftests/kvm/include/x86/ucall.h
> index 0e4950041e3e..3639f03a4da9 100644
> --- a/tools/testing/selftests/kvm/include/x86/ucall.h
> +++ b/tools/testing/selftests/kvm/include/x86/ucall.h
> @@ -2,12 +2,8 @@
>  #ifndef SELFTEST_KVM_UCALL_H
>  #define SELFTEST_KVM_UCALL_H
>  
> -#include "kvm_util.h"
> +#include "linux/kvm.h"

Nit:
#include <linux/kvm.h>

[...]

> +
> +void ucall_arch_do_ucall(gva_t uc)
> +{
> +	return ucall_x86_ops.do_ucall(uc);

return should be dropped.

> +}
> +
> +void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
> +{
> +	return ucall_x86_ops.get_ucall(vcpu);
> +}
>