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This maximum > > size is not checked when page-aligning the RX/TX buffer size, and > > FFA_RXTX_MAP may fail when passed a size greater than the maximum. > > > > Decode the maximum buffer size returned from FFA_FEATURES and limit the > > buffer size based on this value if it is non-zero (zero indicates no > > maximum). Include verification that the max returned by the SPMC is > > larger than the minimum, otherwise use the minimum. > > > > While there, also update RXTX_MAP_MIN_BUFSZ() to use FIELD_GET() for > > consistency. > > > > Fixes: 83210251fd70 ("firmware: arm_ffa: Use the correct buffer size during RXTX_MAP") > > Assisted-by: Claude:claude-opus-4-8 > > Signed-off-by: Seth Forshee > > --- > > drivers/firmware/arm_ffa/driver.c | 29 +++++++++++++++++++++++++++-- > > 1 file changed, 27 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c > > index b9f17fda7243..dc45724a29ba 100644 > > --- a/drivers/firmware/arm_ffa/driver.c > > +++ b/drivers/firmware/arm_ffa/driver.c > > @@ -32,6 +32,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -55,7 +56,9 @@ > > (FIELD_PREP(SENDER_ID_MASK, (s)) | FIELD_PREP(RECEIVER_ID_MASK, (r))) > > > > #define RXTX_MAP_MIN_BUFSZ_MASK GENMASK(1, 0) > > -#define RXTX_MAP_MIN_BUFSZ(x) ((x) & RXTX_MAP_MIN_BUFSZ_MASK) > > +#define RXTX_MAP_MAX_BUFSZ_MASK GENMASK(31, 16) > > +#define RXTX_MAP_MIN_BUFSZ(x) (FIELD_GET(RXTX_MAP_MIN_BUFSZ_MASK, (x))) > > +#define RXTX_MAP_MAX_BUFSZ(x) (FIELD_GET(RXTX_MAP_MAX_BUFSZ_MASK, (x))) > > > > #define FFA_MAX_NOTIFICATIONS 64 > > > > @@ -2086,11 +2089,13 @@ static void ffa_notifications_setup(void) > > ffa_notifications_cleanup(); > > } > > > > +#define FFA_SUPPORTS_RXTX_MAX_BUFSZ(version) ((version) > FFA_VERSION_1_1) > > + > > static int __init ffa_init(void) > > { > > int ret; > > u32 buf_sz; > > - size_t rxtx_bufsz = SZ_4K; > > + size_t rxtx_bufsz = SZ_4K, rxtx_max_bufsz = 0; > > > > ret = ffa_transport_init(&invoke_ffa_fn); > > if (ret) > > @@ -2118,9 +2123,29 @@ static int __init ffa_init(void) > > rxtx_bufsz = SZ_16K; > > else > > rxtx_bufsz = SZ_4K; > > + > > + if (FFA_SUPPORTS_RXTX_MAX_BUFSZ(drv_info->version)) { > > This is not even compile tested ? I don't think this is defined anyway. > Anyways I don't think we need this condition as v1.1 or below had it > MBZ, so it is fine to drop it. It is added just above ffa_init(). The code as been compile and run tested on multiple platforms, as noted in the cover letter. I hadn't checked older spec versions, so if they have it as MBZ then I agree we can drop the check. > > > + rxtx_max_bufsz = (size_t)RXTX_MAP_MAX_BUFSZ(buf_sz) * SZ_4K; > > The cast is unnecessary, its is 16 bit, so max 0xFFFF << 12. Correct, though linters complain about it which is why I added it. I can drop it though if you prefer. > > > > + if (rxtx_max_bufsz != 0 && rxtx_max_bufsz < rxtx_bufsz) { > > + /* > > + * Per spec the maximum must be >= the minimum, or > > + * else zero if there is no size limit. If the SPMC > > + * violates this constraint, use the minimum as the > > + * effective maximum. > > + */ > > I don't see any text implying the above from the spec, drop it. Please point > it to me if you find. Even otherwise it seems obvious here and doesn't need > the note. I found it in v1.3 of the spec in Table 13.15: "Size must be greater or equal to the minimum buffer size, else MBZ if there is no size limit." I will remove the comment. Thanks, Seth