From: Seth Forshee <sforshee@nvidia•com>
To: Sudeep Holla <sudeep.holla@kernel•org>,
Sebastian Ene <sebastianene@google•com>
Cc: linux-arm-kernel@lists•infradead.org,
linux-kernel@vger•kernel.org, Seth Forshee <sforshee@nvidia•com>
Subject: [PATCH v2] firmware: arm_ffa: Handle maximum RX/TX buffer size
Date: Tue, 02 Jun 2026 21:54:06 +0000 [thread overview]
Message-ID: <20260602-b4-ffa-rxtx-map-fixes-v2-1-7cb06508da84@nvidia.com> (raw)
A partition manager may reject unsupported RX/TX buffer sizes by
returning INVALID_PARAMETERS. Commit 83210251fd70 ("firmware: arm_ffa:
Use the correct buffer size during RXTX_MAP") has the effect of rounding
up the buffer size from FFA_FEATURES to be PAGE_SIZE-aligned, which may
be larger than what the partition manager supports. This caused RXTX_MAP
to fail for some FF-A implementations on kernels with PAGE_SIZE > 4K.
In FF-A v1.2+ the partition manager can specify a maximum buffer size via
FFA_FEATURES, but the driver currently doesn't use it. Add support for
decoding and honoring the maximum buffer size.
Some v1.1 implementations also return INVALID_PARAMETERS from RXTX_MAP if
the buffer sizes are too large but lack a mechanism for discovering the
maximum buffer size. The relevant bits must be zero in v1.1 and earlier,
corresponding to "no maximum" in v1.2+, so we can handle both using
the same logic. First, try using a PAGE_SIZE-aligned buffer as is done
now. If this fails with INVALID_PARAMETERS, retry using the minimum
buffer size, which should always be supported.
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 <sforshee@nvidia•com>
---
Changes in v2:
- Combine into one patch.
- Remove unnecessary check for FF-A version when decoding maximum
buffer size, as this field must be zero in earlier versions.
- Simplify the implementation.
- Remove unnecessary typecast.
- Remove unnecessary comments.
- Rebase to for-next/ffa/updates.
- Link to v1: https://patch.msgid.link/20260601-b4-ffa-rxtx-map-fixes-v1-0-c071b12ae05c@nvidia.com
To: Sudeep Holla <sudeep.holla@kernel•org>
To: Sebastian Ene <sebastianene@google•com>
Cc: linux-arm-kernel@lists•infradead.org
Cc: linux-kernel@vger•kernel.org
---
drivers/firmware/arm_ffa/driver.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index 0f468362c288..bc2685331b27 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -32,6 +32,7 @@
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
+#include <linux/minmax.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/mutex.h>
@@ -59,7 +60,9 @@
(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
@@ -2101,7 +2104,7 @@ static int ffa_probe(struct platform_device *pdev)
{
int ret;
u32 buf_sz;
- size_t rxtx_bufsz = SZ_4K;
+ size_t rxtx_min_bufsz = SZ_4K, rxtx_max_bufsz = 0, rxtx_bufsz;
if (IS_BUILTIN(CONFIG_ARM_FFA_TRANSPORT) &&
is_protected_kvm_enabled() && !is_pkvm_initialized())
@@ -2132,15 +2135,18 @@ static int ffa_probe(struct platform_device *pdev)
ret = ffa_features(FFA_FN_NATIVE(RXTX_MAP), 0, &buf_sz, NULL);
if (!ret) {
if (RXTX_MAP_MIN_BUFSZ(buf_sz) == 1)
- rxtx_bufsz = SZ_64K;
+ rxtx_min_bufsz = SZ_64K;
else if (RXTX_MAP_MIN_BUFSZ(buf_sz) == 2)
- rxtx_bufsz = SZ_16K;
+ rxtx_min_bufsz = SZ_16K;
else
- rxtx_bufsz = SZ_4K;
+ rxtx_min_bufsz = SZ_4K;
+
+ rxtx_max_bufsz = RXTX_MAP_MAX_BUFSZ(buf_sz) * SZ_4K;
+ if (rxtx_max_bufsz != 0 && rxtx_max_bufsz < rxtx_min_bufsz)
+ rxtx_max_bufsz = rxtx_min_bufsz;
}
- rxtx_bufsz = PAGE_ALIGN(rxtx_bufsz);
- drv_info->rxtx_bufsz = rxtx_bufsz;
+ rxtx_bufsz = min_not_zero(PAGE_ALIGN(rxtx_min_bufsz), rxtx_max_bufsz);
drv_info->rx_buffer = alloc_pages_exact(rxtx_bufsz, GFP_KERNEL);
if (!drv_info->rx_buffer) {
ret = -ENOMEM;
@@ -2156,10 +2162,17 @@ static int ffa_probe(struct platform_device *pdev)
ret = ffa_rxtx_map(virt_to_phys(drv_info->tx_buffer),
virt_to_phys(drv_info->rx_buffer),
rxtx_bufsz / FFA_PAGE_SIZE);
+ if (ret == -EINVAL && !rxtx_max_bufsz && rxtx_min_bufsz < rxtx_bufsz) {
+ rxtx_bufsz = rxtx_min_bufsz;
+ ret = ffa_rxtx_map(virt_to_phys(drv_info->tx_buffer),
+ virt_to_phys(drv_info->rx_buffer),
+ rxtx_bufsz / FFA_PAGE_SIZE);
+ }
if (ret) {
pr_err("failed to register FFA RxTx buffers\n");
goto free_pages;
}
+ drv_info->rxtx_bufsz = rxtx_bufsz;
mutex_init(&drv_info->rx_lock);
mutex_init(&drv_info->tx_lock);
---
base-commit: 18706ea68fc4344049bf693b702cb311a7c27ca7
change-id: 20260531-b4-ffa-rxtx-map-fixes-244ede71a935
Best regards,
--
Seth Forshee <sforshee@nvidia•com>
next reply other threads:[~2026-06-02 21:54 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-02 21:54 Seth Forshee [this message]
2026-06-03 9:23 ` [PATCH v2] firmware: arm_ffa: Handle maximum RX/TX buffer size Sudeep Holla
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