Re: [PATCH 12/12] xen/arm: ffa: Add message parameter diagnostics

[Jens Wiklander <jens.wiklander@xxxxxxxxxx>]

Hi Bertrand,

On Wed, Feb 11, 2026 at 12:48 PM Bertrand Marquis
<Bertrand.Marquis@xxxxxxx> wrote:
>
> Hi Jens,
>
> > On 11 Feb 2026, at 11:16, Jens Wiklander <jens.wiklander@xxxxxxxxxx> wrote:
> >
> > Hi Bertrand,
> >
> > On Tue, Feb 3, 2026 at 6:38 PM Bertrand Marquis
> > <bertrand.marquis@xxxxxxx> wrote:
> >>
> >> MSG_SEND2 and direct request validation failures are silent, making it
> >> hard to diagnose invalid IDs, oversized messages, or unsupported
> >> destination types.
> >>
> >> Add debug logs for parameter validation failures:
> >> - invalid endpoint IDs
> >> - oversized messages
> >> - unsupported destination types
> >> - invalid sender/receiver combinations
> >> - ratelimit MSG_SEND2 busy failures to avoid log flooding
> >>
> >> No functional changes.
> >>
> >> Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
> >> ---
> >> xen/arch/arm/tee/ffa_msg.c | 45 ++++++++++++++++++++++++++++++++++++++
> >> 1 file changed, 45 insertions(+)
> >>
> >> diff --git a/xen/arch/arm/tee/ffa_msg.c b/xen/arch/arm/tee/ffa_msg.c
> >> index 928f269f6c3a..cc273c9a8e80 100644
> >> --- a/xen/arch/arm/tee/ffa_msg.c
> >> +++ b/xen/arch/arm/tee/ffa_msg.c
> >> @@ -4,6 +4,7 @@
> >>  */
> >>
> >> #include <xen/const.h>
> >> +#include <xen/lib.h>
> >> #include <xen/sizes.h>
> >> #include <xen/types.h>
> >>
> >> @@ -100,6 +101,7 @@ void ffa_handle_msg_send_direct_req(struct 
> >> cpu_user_regs *regs, uint32_t fid)
> >>     if ( !ffa_fw_supports_fid(fid) )
> >>     {
> >>         ret = FFA_RET_NOT_SUPPORTED;
> >> +        gdprintk(XENLOG_DEBUG, "ffa: direct req fid %#x not supported\n", 
> >> fid);
> >>         goto out;
> >>     }
> >>
> >> @@ -108,6 +110,9 @@ void ffa_handle_msg_send_direct_req(struct 
> >> cpu_user_regs *regs, uint32_t fid)
> >>          (src_dst & GENMASK(15,0)) == ffa_get_vm_id(d) )
> >>     {
> >>         ret = FFA_RET_INVALID_PARAMETERS;
> >> +        gdprintk(XENLOG_DEBUG,
> >> +                 "ffa: direct req invalid src/dst %#x\n",
> >> +                 (uint32_t)src_dst);
> >>         goto out;
> >>     }
> >>
> >> @@ -115,6 +120,9 @@ void ffa_handle_msg_send_direct_req(struct 
> >> cpu_user_regs *regs, uint32_t fid)
> >>     if ( !FFA_ID_IS_SECURE(src_dst & GENMASK(15,0)) )
> >>     {
> >>         ret = FFA_RET_NOT_SUPPORTED;
> >> +        gdprintk(XENLOG_DEBUG,
> >> +                 "ffa: direct req to non-secure dst %#x\n",
> >> +                 (uint32_t)(src_dst & GENMASK(15, 0)));
> >>         goto out;
> >>     }
> >>
> >> @@ -166,7 +174,12 @@ static int32_t ffa_msg_send2_vm(uint16_t dst_id, 
> >> const void *src_buf,
> >>     /* This is also checking that dest is not src */
> >>     ret = ffa_endpoint_domain_lookup(dst_id, &dst_d, &dst_ctx);
> >>     if ( ret )
> >> +    {
> >> +        gdprintk(XENLOG_DEBUG,
> >> +                 "ffa: msg_send2 lookup failed: dst %#x ret %d\n",
> >> +                 dst_id, ret);
> >>         return ret;
> >> +    }
> >>
> >>     /* This also checks that destination has set a Rx buffer */
> >>     ret = ffa_rx_acquire(dst_ctx , &rx_buf, &rx_size);
> >> @@ -199,6 +212,12 @@ static int32_t ffa_msg_send2_vm(uint16_t dst_id, 
> >> const void *src_buf,
> >>     /* receiver rx buffer will be released by the receiver*/
> >>
> >> out_unlock:
> >> +    if ( ret )
> >> +    {
> >> +        if ( ret != FFA_RET_BUSY || printk_ratelimit() )
> >
> > Shouldn't this be && ?
>
> The intent here is to log all non BUSY errors but only log BUSY when 
> ratelimit allows
> to reduce the amount of logs in case of someone polling when the receiver RX 
> buffer
> is busy.
>
> Maybe I should add a comment to make that clearer ?

Yes, please.

Cheers,
Jens

>
> Cheers
> Bertrand
>
> >
> > Cheers,
> > Jens
> >
> >> +            gdprintk(XENLOG_DEBUG, "ffa: msg_send2 to %#x failed: %d\n",
> >> +                     dst_id, ret);
> >> +    }
> >>     rcu_unlock_domain(dst_d);
> >>     if ( !ret )
> >>         ffa_raise_rx_buffer_full(dst_d);
> >> @@ -226,7 +245,11 @@ int32_t ffa_handle_msg_send2(struct cpu_user_regs 
> >> *regs)
> >>
> >>     ret = ffa_tx_acquire(src_ctx, &tx_buf, &tx_size);
> >>     if ( ret != FFA_RET_OK )
> >> +    {
> >> +        gdprintk(XENLOG_DEBUG,
> >> +                 "ffa: msg_send2 TX acquire failed: %d\n", ret);
> >>         return ret;
> >> +    }
> >>
> >>     /* create a copy of the message header */
> >>     memcpy(&src_msg, tx_buf, sizeof(src_msg));
> >> @@ -238,6 +261,9 @@ int32_t ffa_handle_msg_send2(struct cpu_user_regs 
> >> *regs)
> >>          dst_id == ffa_get_vm_id(src_d) )
> >>     {
> >>         ret = FFA_RET_INVALID_PARAMETERS;
> >> +        gdprintk(XENLOG_DEBUG,
> >> +                 "ffa: msg_send2 invalid src/dst src %#x dst %#x\n",
> >> +                 src_id, dst_id);
> >>         goto out;
> >>     }
> >>
> >> @@ -246,6 +272,9 @@ int32_t ffa_handle_msg_send2(struct cpu_user_regs 
> >> *regs)
> >>         if (src_msg.msg_offset < sizeof(struct ffa_part_msg_rxtx_1_1))
> >>         {
> >>             ret = FFA_RET_INVALID_PARAMETERS;
> >> +            gdprintk(XENLOG_DEBUG,
> >> +                     "ffa: msg_send2 invalid msg_offset %u (v1.1)\n",
> >> +                     src_msg.msg_offset);
> >>             goto out;
> >>         }
> >>         /* Set uuid to Nil UUID for v1.1 guests */
> >> @@ -255,6 +284,9 @@ int32_t ffa_handle_msg_send2(struct cpu_user_regs 
> >> *regs)
> >>     else if ( src_msg.msg_offset < sizeof(struct ffa_part_msg_rxtx_1_2) )
> >>     {
> >>         ret = FFA_RET_INVALID_PARAMETERS;
> >> +        gdprintk(XENLOG_DEBUG,
> >> +                 "ffa: msg_send2 invalid msg_offset %u (v1.2)\n",
> >> +                 src_msg.msg_offset);
> >>         goto out;
> >>     }
> >>
> >> @@ -263,6 +295,9 @@ int32_t ffa_handle_msg_send2(struct cpu_user_regs 
> >> *regs)
> >>             src_msg.msg_size > (tx_size - src_msg.msg_offset) )
> >>     {
> >>         ret = FFA_RET_INVALID_PARAMETERS;
> >> +        gdprintk(XENLOG_DEBUG,
> >> +                 "ffa: msg_send2 invalid msg_size %u offset %u tx %zu\n",
> >> +                 src_msg.msg_size, src_msg.msg_offset, tx_size);
> >>         goto out;
> >>     }
> >>
> >> @@ -272,6 +307,8 @@ int32_t ffa_handle_msg_send2(struct cpu_user_regs 
> >> *regs)
> >>         if ( !ffa_fw_supports_fid(FFA_MSG_SEND2) )
> >>         {
> >>             ret = FFA_RET_NOT_SUPPORTED;
> >> +            gdprintk(XENLOG_DEBUG,
> >> +                     "ffa: msg_send2 to SP not supported\n");
> >>             goto out;
> >>         }
> >>         /*
> >> @@ -288,6 +325,8 @@ int32_t ffa_handle_msg_send2(struct cpu_user_regs 
> >> *regs)
> >>
> >>         ret = ffa_simple_call(FFA_MSG_SEND2,
> >>                               ((uint32_t)ffa_get_vm_id(src_d)) << 16, 0, 
> >> 0, 0);
> >> +        if ( ret )
> >> +            gdprintk(XENLOG_DEBUG, "ffa: msg_send2 to SP failed: %d\n", 
> >> ret);
> >>     }
> >>     else if ( IS_ENABLED(CONFIG_FFA_VM_TO_VM) )
> >>     {
> >> @@ -295,7 +334,11 @@ int32_t ffa_handle_msg_send2(struct cpu_user_regs 
> >> *regs)
> >>         ret = ffa_msg_send2_vm(dst_id, tx_buf, &src_msg);
> >>     }
> >>     else
> >> +    {
> >>         ret = FFA_RET_INVALID_PARAMETERS;
> >> +        gdprintk(XENLOG_DEBUG,
> >> +                 "ffa: msg_send2 to VM disabled (dst %#x)\n", dst_id);
> >> +    }
> >>
> >> out:
> >>     ffa_tx_release(src_ctx);
> >> @@ -311,6 +354,7 @@ void ffa_handle_run(struct cpu_user_regs *regs, 
> >> uint32_t fid)
> >>     if ( !ffa_fw_supports_fid(fid) )
> >>     {
> >>         ret = FFA_RET_NOT_SUPPORTED;
> >> +        gdprintk(XENLOG_DEBUG, "ffa: run fid %#x not supported\n", fid);
> >>         goto out;
> >>     }
> >>
> >> @@ -322,6 +366,7 @@ void ffa_handle_run(struct cpu_user_regs *regs, 
> >> uint32_t fid)
> >>     if ( !FFA_ID_IS_SECURE(dst >> 16) )
> >>     {
> >>         ret = FFA_RET_NOT_SUPPORTED;
> >> +        gdprintk(XENLOG_DEBUG, "ffa: run to non-secure dst %#x\n", dst);
> >>         goto out;
> >>     }
> >>
> >> --
> >> 2.50.1 (Apple Git-155)
> >>
>