Re: [Qemu-devel] [PATCH V3 2/2] target-arm: Guest cpu endianness determination for virtio KVM ARM/ARM64

[Peter Maydell]

On 5 February 2015 at 09:59, Pranavkumar Sawargaonkar
<address@hidden> wrote:
> This patch implements a fucntion pointer "virtio_is_big_endian"
> from "CPUClass" structure for arm/arm64.
> Function arm_cpu_is_big_endian() is added to determine and
> return the guest cpu endianness to virtio.
> This is required for running cross endian guests with virtio on ARM/ARM64.
>
> Signed-off-by: Pranavkumar Sawargaonkar <address@hidden>
> ---
>  target-arm/cpu.c | 24 ++++++++++++++++++++++++
>  target-arm/cpu.h |  2 ++
>  2 files changed, 26 insertions(+)
>
> diff --git a/target-arm/cpu.c b/target-arm/cpu.c
> index 285947f..4d9cded 100644
> --- a/target-arm/cpu.c
> +++ b/target-arm/cpu.c
> @@ -320,6 +320,29 @@ static void arm_cpu_kvm_set_irq(void *opaque, int irq, 
> int level)
>      kvm_set_irq(kvm_state, kvm_irq, level ? 1 : 0);
>  #endif
>  }
> +
> +static bool arm_cpu_is_big_endian(CPUState *cs)
> +{
> +    ARMCPU *cpu = ARM_CPU(cs);
> +    CPUARMState *env = &cpu->env;
> +    int cur_el;
> +
> +    cpu_synchronize_state(cs);
> +
> +    /* In 32bit guest endianess is determined by looking at CPSR's E bit */
> +    if (!is_a64(env)) {
> +        return (env->pstate & CPSR_E) ? 1 : 0;

This is wrong, because if we're not 32-bit then the CPSR
isn't in env->pstate but in env->cpsr_uncached. (I'm guessing
you didn't test 32-bit guests.)

Since this is the only error in this patch, I'll just fix it
as I put the series into target-arm.next rather than forcing
you to respin it.

thanks
-- PMM