Re: [PATCH 2/2] x86/cpu: Handle GUEST_MAXPHYADDR < HOST_MAXPHYADDR for hosts that don't support it

[Paolo Bonzini]

On 19/06/20 17:53, Mohammed Gamal wrote:
> If the CPU doesn't support GUEST_MAXPHYADDR < HOST_MAXPHYADDR we
> let QEMU choose to use the host MAXPHYADDR and print a warning to the
> user.
> 
> Signed-off-by: Mohammed Gamal <mgamal@redhat.com>
> ---
>  target/i386/cpu.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index b1b311baa2..91c57117ce 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -6589,6 +6589,17 @@ static void x86_cpu_realizefn(DeviceState *dev, Error 
> **errp)
>              uint32_t host_phys_bits = x86_host_phys_bits();
>              static bool warned;
>  
> +         /*
> +          * If host doesn't support setting physical bits on the guest,
> +          * report it and return
> +          */
> +         if (cpu->phys_bits < host_phys_bits &&
> +             !kvm_has_smaller_maxphyaddr()) {
> +             warn_report("Host doesn't support setting smaller phys-bits."
> +                         " Using host phys-bits\n");
> +             cpu->phys_bits = host_phys_bits;
> +         }
> +
>              /* Print a warning if the user set it to a value that's not the
>               * host value.
>               */
> 

You should remove the existing warning too.

Paolo