Re: [Qemu-devel] [PATCH 4/5] x86: Allow physical address bits to be set

[Paolo Bonzini]

On 16/06/2016 19:12, Dr. David Alan Gilbert (git) wrote:
>          if (env->features[FEAT_8000_0001_EDX] & CPUID_EXT2_LM) {
> -            /* 64 bit processor */
> -/* XXX: The physical address space is limited to 42 bits in exec.c. */
> -            *eax = 0x00003028; /* 48 bits virtual, 40 bits physical */
> +            /* 64 bit processor, 48 bits virtual, configurable
> +             * physical bits.
> +             */
> +            *eax = 0x00003000 + cpu->phys_bits;

This probably ought to be range checked in realize.  I think you can
also implement the magic 0 value there and have a bit less indentation.

In addition, "-cpu host" should have phys-bits=0.

Otherwise looks great.

Paolo

>          } else {
>              if (env->features[FEAT_1_EDX] & CPUID_PSE36) {
>                  *eax = 0x00000024; /* 36 bits physical */
> @@ -3273,6 +3274,7 @@ static Property x86_cpu_properties[] = {
>      DEFINE_PROP_BOOL("enforce", X86CPU, enforce_cpuid, false),
>      DEFINE_PROP_BOOL("kvm", X86CPU, expose_kvm, true),
>      DEFINE_PROP_BOOL("fill-mtrr-mask", X86CPU, fill_mtrr_mask, true),
> +    DEFINE_PROP_UINT32("phys-bits", X86CPU, phys_bits, 40),
>      DEFINE_PROP_UINT32("level", X86CPU, env.cpuid_level, 0),
>      DEFINE_PROP_UINT32("xlevel", X86CPU, env.cpuid_xlevel, 0),
>      DEFINE_PROP_UINT32("xlevel2", X86CPU, env.cpuid_xlevel2, 0),
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index 13d8501..fccba72 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -1184,6 +1184,9 @@ struct X86CPU {
>      /* if true fill the top bits of the MTRR_PHYSMASKn variable range */
>      bool fill_mtrr_mask;
>  
> +    /* Number of physical address bits supported */
> +    uint32_t phys_bits;