Re: [PATCH] WHPX: Use QEMU values for trapped CPUID

[Paolo Bonzini <pbonzini@redhat.com>]

On 27/02/20 22:01, Sunil Muthuswamy wrote:
> Currently, WHPX is using some default values for the trapped CPUID
> functions. These were not in sync with the QEMU values because the
> CPUID values were never set with WHPX during VCPU initialization.
> Additionally, at the moment, WHPX doesn't support setting CPUID
> values in the hypervisor at runtime (i.e. after the partition has
> been setup). That is needed to be able to set the CPUID values in
> the hypervisor during VCPU init.
> Until that support comes, use the QEMU values for the trapped CPUIDs.
> 
> Signed-off-by: Sunil Muthuswamy <sunilmut@microsoft.com>
> ---
>  target/i386/whpx-all.c | 42 ++++++++++++++++++------------------------
>  1 file changed, 18 insertions(+), 24 deletions(-)
> 
> diff --git a/target/i386/whpx-all.c b/target/i386/whpx-all.c
> index 35601b8176..4fe5a78b29 100644
> --- a/target/i386/whpx-all.c
> +++ b/target/i386/whpx-all.c
> @@ -980,38 +980,32 @@ static int whpx_vcpu_run(CPUState *cpu)
>              WHV_REGISTER_VALUE reg_values[5];
>              WHV_REGISTER_NAME reg_names[5];
>              UINT32 reg_count = 5;
> -            UINT64 rip, rax, rcx, rdx, rbx;
> +            UINT64 cpuid_fn, rip = 0, rax = 0, rcx = 0, rdx = 0, rbx = 0;
> +            X86CPU *x86_cpu = X86_CPU(cpu);
> +            CPUX86State *env = &x86_cpu->env;
>  
>              memset(reg_values, 0, sizeof(reg_values));
>  
>              rip = vcpu->exit_ctx.VpContext.Rip +
>                    vcpu->exit_ctx.VpContext.InstructionLength;
> -            switch (vcpu->exit_ctx.CpuidAccess.Rax) {
> -            case 1:
> -                rax = vcpu->exit_ctx.CpuidAccess.DefaultResultRax;
> -                /* Advertise that we are running on a hypervisor */
> -                rcx =
> -                    vcpu->exit_ctx.CpuidAccess.DefaultResultRcx |
> -                    CPUID_EXT_HYPERVISOR;
> -
> -                rdx = vcpu->exit_ctx.CpuidAccess.DefaultResultRdx;
> -                rbx = vcpu->exit_ctx.CpuidAccess.DefaultResultRbx;
> -                break;
> +            cpuid_fn = vcpu->exit_ctx.CpuidAccess.Rax;
> +
> +            /*
> +             * Ideally, these should be supplied to the hypervisor during VCPU
> +             * initialization and it should be able to satisfy this request.
> +             * But, currently, WHPX doesn't support setting CPUID values in the
> +             * hypervisor once the partition has been setup, which is too late
> +             * since VCPUs are realized later. For now, use the values from
> +             * QEMU to satisfy these requests, until WHPX adds support for
> +             * being able to set these values in the hypervisor at runtime.
> +             */
> +            cpu_x86_cpuid(env, cpuid_fn, 0, (UINT32 *)&rax, (UINT32 *)&rbx,
> +                (UINT32 *)&rcx, (UINT32 *)&rdx);
> +            switch (cpuid_fn) {
>              case 0x80000001:
> -                rax = vcpu->exit_ctx.CpuidAccess.DefaultResultRax;
>                  /* Remove any support of OSVW */
> -                rcx =
> -                    vcpu->exit_ctx.CpuidAccess.DefaultResultRcx &
> -                    ~CPUID_EXT3_OSVW;
> -
> -                rdx = vcpu->exit_ctx.CpuidAccess.DefaultResultRdx;
> -                rbx = vcpu->exit_ctx.CpuidAccess.DefaultResultRbx;
> +                rcx &= ~CPUID_EXT3_OSVW;
>                  break;
> -            default:
> -                rax = vcpu->exit_ctx.CpuidAccess.DefaultResultRax;
> -                rcx = vcpu->exit_ctx.CpuidAccess.DefaultResultRcx;
> -                rdx = vcpu->exit_ctx.CpuidAccess.DefaultResultRdx;
> -                rbx = vcpu->exit_ctx.CpuidAccess.DefaultResultRbx;
>              }
>  
>              reg_names[0] = WHvX64RegisterRip;
> 

Queued if you need that, thanks.

Paolo