Re: [XEN PATCH v10 11/24] xen/arm: ffa: map SPMC rx/tx buffers

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi Jens,

> On 17 Jul 2023, at 09:20, Jens Wiklander <jens.wiklander@xxxxxxxxxx> wrote:
> 
> When initializing the FF-A mediator map the RX and TX buffers shared with
> the SPMC.
> 
> These buffer are later used to to transmit data that cannot be passed in
> registers only.
> 
> Adds a check that the SP supports the needed FF-A features
> FFA_RXTX_MAP_64 and FFA_RXTX_UNMAP.
> 
> Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>

Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>

Cheers
Bertrand

> ---
> xen/arch/arm/tee/ffa.c | 50 +++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 49 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/tee/ffa.c b/xen/arch/arm/tee/ffa.c
> index e05d58cf7755..f8ccaabc568d 100644
> --- a/xen/arch/arm/tee/ffa.c
> +++ b/xen/arch/arm/tee/ffa.c
> @@ -12,6 +12,7 @@
> #include <xen/errno.h>
> #include <xen/init.h>
> #include <xen/lib.h>
> +#include <xen/mm.h>
> #include <xen/sched.h>
> #include <xen/sizes.h>
> #include <xen/types.h>
> @@ -67,6 +68,12 @@
>  */
> #define FFA_PAGE_SIZE                   SZ_4K
> 
> +/*
> + * The number of pages used for each of the RX and TX buffers shared with
> + * the SPMC.
> + */
> +#define FFA_RXTX_PAGE_COUNT             1
> +
> /*
>  * Flags and field values used for the MSG_SEND_DIRECT_REQ/RESP:
>  * BIT(31): Framework or partition message
> @@ -161,6 +168,13 @@ struct ffa_ctx {
> /* Negotiated FF-A version to use with the SPMC */
> static uint32_t __ro_after_init ffa_version;
> 
> +/*
> + * Our rx/tx buffers shared with the SPMC. FFA_RXTX_PAGE_COUNT is the
> + * number of pages used in each of these buffers.
> + */
> +static void *ffa_rx __read_mostly;
> +static void *ffa_tx __read_mostly;
> +
> static bool ffa_get_version(uint32_t *vers)
> {
>     const struct arm_smccc_1_2_regs arg = {
> @@ -231,6 +245,12 @@ static bool check_mandatory_feature(uint32_t id)
>     return !ret;
> }
> 
> +static int32_t ffa_rxtx_map(paddr_t tx_addr, paddr_t rx_addr,
> +                            uint32_t page_count)
> +{
> +    return ffa_simple_call(FFA_RXTX_MAP_64, tx_addr, rx_addr, page_count, 0);
> +}
> +
> static uint16_t get_vm_id(const struct domain *d)
> {
>     /* +1 since 0 is reserved for the hypervisor in FF-A */
> @@ -394,6 +414,7 @@ static int ffa_relinquish_resources(struct domain *d)
> static bool ffa_probe(void)
> {
>     uint32_t vers;
> +    int e;
>     unsigned int major_vers;
>     unsigned int minor_vers;
> 
> @@ -441,12 +462,39 @@ static bool ffa_probe(void)
>      * TODO: Rework the code to allow domain to use a subset of the
>      * features supported.
>      */
> -    if ( !check_mandatory_feature(FFA_MSG_SEND_DIRECT_REQ_32) )
> +    if (
> +         !check_mandatory_feature(FFA_RXTX_MAP_64) ||
> +         !check_mandatory_feature(FFA_RXTX_UNMAP) ||
> +         !check_mandatory_feature(FFA_MSG_SEND_DIRECT_REQ_32) )
> +        return false;
> +
> +    ffa_rx = alloc_xenheap_pages(get_order_from_pages(FFA_RXTX_PAGE_COUNT), 
> 0);
> +    if ( !ffa_rx )
>         return false;
> 
> +    ffa_tx = alloc_xenheap_pages(get_order_from_pages(FFA_RXTX_PAGE_COUNT), 
> 0);
> +    if ( !ffa_tx )
> +        goto err_free_ffa_rx;
> +
> +    e = ffa_rxtx_map(__pa(ffa_tx), __pa(ffa_rx), FFA_RXTX_PAGE_COUNT);
> +    if ( e )
> +    {
> +        printk(XENLOG_ERR "ffa: Failed to map rxtx: error %d\n", e);
> +        goto err_free_ffa_tx;
> +    }
>     ffa_version = vers;
> 
>     return true;
> +
> +err_free_ffa_tx:
> +    free_xenheap_pages(ffa_tx, 0);
> +    ffa_tx = NULL;
> +err_free_ffa_rx:
> +    free_xenheap_pages(ffa_rx, 0);
> +    ffa_rx = NULL;
> +    ffa_version = 0;
> +
> +    return false;
> }
> 
> static const struct tee_mediator_ops ffa_ops =
> -- 
> 2.34.1
>