nvme: Invalidate dcache before submitting admin cmd
This patch try to avoids eviction of dirty lines during DMA
transfer. The code right now execute the following step:
- allocate the buffer
- start a dma operation using the non-coherent dma buffer
- invalidate cache lines associated with the buffer
- read the buffer
This can lead to reading back not valid information, because the cache
controller could evict dirty cache lines belonging to the buffer *after*
the DMA operation has started to fill the DRAM.
In order to avoid this, a new invalidation is required *before* starting
the DMA operation. The patch just adds an invalidation before submitting
the DMA command.
Example below shows the nvme disk scan result without the following
patch
=> nvme scan
nvme_get_info_from_identify: nn = 544502629, vwc = 100,
sn = dev_0T, mn = `�\�, fr = t_part, mdts = 105
So, invalidating the cache before submitting the admin command,
fix the cpu read.
Cc: André Przywara <andre.przywara@arm.com>
Reported-by: Suniel Mahesh <sunil@amarulasolutions.com>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Suniel Mahesh <sunil@amarulasolutions.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/nvme/nvme.c b/drivers/nvme/nvme.c
index 0357aba..fc64d93 100644
--- a/drivers/nvme/nvme.c
+++ b/drivers/nvme/nvme.c
@@ -466,6 +466,9 @@
c.identify.cns = cpu_to_le32(cns);
+ invalidate_dcache_range(dma_addr,
+ dma_addr + sizeof(struct nvme_id_ctrl));
+
ret = nvme_submit_admin_cmd(dev, &c, NULL);
if (!ret)
invalidate_dcache_range(dma_addr,