Re: [PATCH 08/18] arm/altp2m: Add HVMOP_altp2m_destroy_p2m.

[Julien Grall <julien.grall@arm.com>]

Hello Sergej,

On 04/07/16 12:45, Sergej Proskurin wrote:
> Signed-off-by: Sergej Proskurin <proskurin@sec.in.tum.de>
> ---
> Cc: Stefano Stabellini <sstabellini@kernel.org>
> Cc: Julien Grall <julien.grall@arm.com>
> ---
>   xen/arch/arm/hvm.c        |  2 +-
>   xen/arch/arm/p2m.c        | 32 ++++++++++++++++++++++++++++++++
>   xen/include/asm-arm/p2m.h |  3 +++
>   3 files changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/hvm.c b/xen/arch/arm/hvm.c
> index 005d7c6..f4ec5cf 100644
> --- a/xen/arch/arm/hvm.c
> +++ b/xen/arch/arm/hvm.c
> @@ -145,7 +145,7 @@ static int do_altp2m_op(XEN_GUEST_HANDLE_PARAM(void) arg)
>           break;
>
>       case HVMOP_altp2m_destroy_p2m:
> -        rc = -EOPNOTSUPP;
> +        rc = p2m_destroy_altp2m_by_id(d, a.u.view.view);
>           break;
>
>       case HVMOP_altp2m_switch_p2m:
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 6c41b98..f82f1ea 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -2200,6 +2200,38 @@ void p2m_flush_altp2m(struct domain *d)
>       altp2m_unlock(d);
>   }
>
> +int p2m_destroy_altp2m_by_id(struct domain *d, unsigned int idx)
> +{
> +    struct p2m_domain *p2m;
> +    int rc = -EBUSY;
> +
> +    if ( !idx || idx >= MAX_ALTP2M )

Can you please add a comment to explain why the altp2m at index 0 cannot 
be destroyed.

> +        return rc;
> +
> +    domain_pause_except_self(d);
> +
> +    altp2m_lock(d);
> +
> +    if ( d->arch.altp2m_vttbr[idx] != INVALID_MFN )
> +    {
> +        p2m = d->arch.altp2m_p2m[idx];
> +
> +        if ( !_atomic_read(p2m->active_vcpus) )
> +        {
> +            p2m_flush_table(p2m);
> +            flush_tlb();

Can you explain this call? flush_tlb is flushing TLBs for the current 
VMID only. However, d may not be equal to current when calling from HVM op.

> +            d->arch.altp2m_vttbr[idx] = INVALID_MFN;
> +            rc = 0;
> +        }
> +    }
> +
> +    altp2m_unlock(d);
> +
> +    domain_unpause_except_self(d);
> +
> +    return rc;
> +}
> +
>   /*
>    * Local variables:
>    * mode: C
> diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
> index c51532a..255a282 100644
> --- a/xen/include/asm-arm/p2m.h
> +++ b/xen/include/asm-arm/p2m.h
> @@ -140,6 +140,9 @@ int p2m_init_altp2m_by_id(struct domain *d, unsigned int idx);
>   /* Find an available alternate p2m and make it valid */
>   int p2m_init_next_altp2m(struct domain *d, uint16_t *idx);
>
> +/* Make a specific alternate p2m invalid */
> +int p2m_destroy_altp2m_by_id(struct domain *d, unsigned int idx);
> +
>   #define p2m_is_foreign(_t)  ((_t) == p2m_map_foreign)
>   #define p2m_is_ram(_t)      ((_t) == p2m_ram_rw || (_t) == p2m_ram_ro)
>
>

Regards,

-- 
Julien Grall

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