Re: [PATCH] mask out clflush

[Anthony Liguori <anthony@codemonkey.ws>]

Glauber Costa wrote:
> clflush is a non-privileged instruction that flushes the cacheline
> given by its parameter, in terms of linear address. As it is non-privileged,
> it is quite tricky, because a guest doing clflush will actually be trying to
> flush a host kernel address.
>   

Is this the case still with NPT/EPT?

Regards,

Anthony Liguori

> Signed-off-by: Glauber Costa <gcosta@redhat.com>
> ---
>  qemu/qemu-kvm-x86.c |   12 ++++++++----
>  1 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/qemu/qemu-kvm-x86.c b/qemu/qemu-kvm-x86.c
> index 5daedd1..7f90fc2 100644
> --- a/qemu/qemu-kvm-x86.c
> +++ b/qemu/qemu-kvm-x86.c
> @@ -505,13 +505,17 @@ static void do_cpuid_ent(struct kvm_cpuid_entry *e, uint32_t function,
>  	e->ecx = bcd[1];
>  	e->edx = bcd[2];
>      }
> -    // "Hypervisor present" bit for Microsoft guests
> -    if (function == 1)
> -	e->ecx |= (1u << 31);
> +
> +    if (function == 1) {
> +        // "Hypervisor present" bit for Microsoft guests
> +        e->ecx |= (1u << 31);
> +        e->edx &= ~(1u << 19);
> +    }
>  
>      // 3dnow isn't properly emulated yet
>      if (function == 0x80000001)
> -	e->edx &= ~0xc0000000;
> +        e->edx &= ~0xc0000000;
> +
>  }
>  
>  struct kvm_para_features {
>