6.12-stable review patch. If anyone has any objections, please let me know.
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From: Emil Tantilov emil.s.tantilov@intel.com
[ Upstream commit 396f0165672c6a74d7379027d344b83b5f05948c ]
Add read memory barrier to ensure the order of operations when accessing control queue descriptors. Specifically, we want to avoid cases where loads can be reordered:
1. Load #1 is dispatched to read descriptor flags. 2. Load #2 is dispatched to read some other field from the descriptor. 3. Load #2 completes, accessing memory/cache at a point in time when the DD flag is zero. 4. NIC DMA overwrites the descriptor, now the DD flag is one. 5. Any fields loaded before step 4 are now inconsistent with the actual descriptor state.
Add read memory barrier between steps 1 and 2, so that load #2 is not executed until load #1 has completed.
Fixes: 8077c727561a ("idpf: add controlq init and reset checks") Reviewed-by: Przemek Kitszel przemyslaw.kitszel@intel.com Reviewed-by: Sridhar Samudrala sridhar.samudrala@intel.com Suggested-by: Lance Richardson rlance@google.com Signed-off-by: Emil Tantilov emil.s.tantilov@intel.com Tested-by: Krishneil Singh krishneil.k.singh@intel.com Signed-off-by: Tony Nguyen anthony.l.nguyen@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/intel/idpf/idpf_controlq.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/net/ethernet/intel/idpf/idpf_controlq.c b/drivers/net/ethernet/intel/idpf/idpf_controlq.c index 4849590a5591f..b28991dd18703 100644 --- a/drivers/net/ethernet/intel/idpf/idpf_controlq.c +++ b/drivers/net/ethernet/intel/idpf/idpf_controlq.c @@ -376,6 +376,9 @@ int idpf_ctlq_clean_sq(struct idpf_ctlq_info *cq, u16 *clean_count, if (!(le16_to_cpu(desc->flags) & IDPF_CTLQ_FLAG_DD)) break;
+ /* Ensure no other fields are read until DD flag is checked */ + dma_rmb(); + /* strip off FW internal code */ desc_err = le16_to_cpu(desc->ret_val) & 0xff;
@@ -563,6 +566,9 @@ int idpf_ctlq_recv(struct idpf_ctlq_info *cq, u16 *num_q_msg, if (!(flags & IDPF_CTLQ_FLAG_DD)) break;
+ /* Ensure no other fields are read until DD flag is checked */ + dma_rmb(); + q_msg[i].vmvf_type = (flags & (IDPF_CTLQ_FLAG_FTYPE_VM | IDPF_CTLQ_FLAG_FTYPE_PF)) >>