Re: [Xen-devel] [PATCH v2 07/17] arm64: vgic-v3: Add ICV_EOIR1_EL1 handler

[Marc Zyngier <marc.zyngier@xxxxxxx>]

On 27/03/18 10:07, Manish Jaggi wrote:
> This patch is ported to xen from linux commit
> b6f49035b4bf6e2709f2a5fed3107f5438c1fd02
> KVM: arm64: vgic-v3: Add ICV_EOIR1_EL1 handler
> 
> Add a handler for writing the guest's view of the ICC_EOIR1_EL1
> register. This involves dropping the priority of the interrupt,
> and deactivating it if required (EOImode == 0).
> 
> Signed-off-by : Manish Jaggi <manish.jaggi@xxxxxxxxxx>
> ---
>  xen/arch/arm/arm64/vgic-v3-sr.c     | 136 
> ++++++++++++++++++++++++++++++++++++
>  xen/include/asm-arm/arm64/sysregs.h |   1 +
>  xen/include/asm-arm/gic_v3_defs.h   |   4 ++
>  3 files changed, 141 insertions(+)
> 
> diff --git a/xen/arch/arm/arm64/vgic-v3-sr.c b/xen/arch/arm/arm64/vgic-v3-sr.c
> index 026d64506f..e32ec01f56 100644
> --- a/xen/arch/arm/arm64/vgic-v3-sr.c
> +++ b/xen/arch/arm/arm64/vgic-v3-sr.c
> @@ -33,6 +33,7 @@
>  
>  #define ICC_IAR1_EL1_SPURIOUS    0x3ff
>  #define VGIC_MAX_SPI             1019
> +#define VGIC_MIN_LPI             8192
>  
>  static int vgic_v3_bpr_min(void)
>  {
> @@ -482,6 +483,137 @@ static void vreg_emulate_iar(struct cpu_user_regs 
> *regs, const union hsr hsr)
>      vgic_v3_read_iar(regs, hsr);
>  }
>  
> +static int vgic_v3_find_active_lr(int intid, uint64_t *lr_val)
> +{
> +    int i;
> +    unsigned int used_lrs =  gic_get_num_lrs();

This is quite a departure from the existing code. KVM always allocate
LRs sequentially, and used_lrs represents the current upper bound. Here,
you seem to be looking at *all* the LRs. Is that safe? Are you
guaranteed not to have any stale state?

In any case, the change should be documented.

> +
> +    for ( i = 0; i < used_lrs; i++ )
> +    {
> +        uint64_t val = gicv3_ich_read_lr(i);
> +
> +        if ( (val & ICH_LR_VIRTUAL_ID_MASK) == intid &&
> +            (val & ICH_LR_ACTIVE_BIT) )
> +        {
> +            *lr_val = val;
> +            return i;
> +        }
> +    }
> +
> +    *lr_val = ICC_IAR1_EL1_SPURIOUS;
> +    return -1;
> +}

Thanks,

        M.
-- 
Jazz is not dead. It just smells funny...

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