[PATCH 5.12 042/384] mmc: sdhci: Check for reset prior to DMA address unmap

From: Greg Kroah-Hartman
Date: Mon May 10 2021 - 08:05:28 EST


From: Pradeep P V K <pragalla@xxxxxxxxxxxxxx>

commit 21e35e898aa9ef7781632959db8613a5380f2eae upstream.

For data read commands, SDHC may initiate data transfers even before it
completely process the command response. In case command itself fails,
driver un-maps the memory associated with data transfer but this memory
can still be accessed by SDHC for the already initiated data transfer.
This scenario can lead to un-mapped memory access error.

To avoid this scenario, reset SDHC (when command fails) prior to
un-mapping memory. Resetting SDHC ensures that all in-flight data
transfers are either aborted or completed. So we don't run into this
scenario.

Swap the reset, un-map steps sequence in sdhci_request_done().

Suggested-by: Veerabhadrarao Badiganti <vbadigan@xxxxxxxxxxxxxx>
Signed-off-by: Pradeep P V K <pragalla@xxxxxxxxxxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Link: https://lore.kernel.org/r/1614760331-43499-1-git-send-email-pragalla@xxxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx # v4.9+
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/mmc/host/sdhci.c | 60 ++++++++++++++++++++++++-----------------------
1 file changed, 31 insertions(+), 29 deletions(-)

--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2997,6 +2997,37 @@ static bool sdhci_request_done(struct sd
}

/*
+ * The controller needs a reset of internal state machines
+ * upon error conditions.
+ */
+ if (sdhci_needs_reset(host, mrq)) {
+ /*
+ * Do not finish until command and data lines are available for
+ * reset. Note there can only be one other mrq, so it cannot
+ * also be in mrqs_done, otherwise host->cmd and host->data_cmd
+ * would both be null.
+ */
+ if (host->cmd || host->data_cmd) {
+ spin_unlock_irqrestore(&host->lock, flags);
+ return true;
+ }
+
+ /* Some controllers need this kick or reset won't work here */
+ if (host->quirks & SDHCI_QUIRK_CLOCK_BEFORE_RESET)
+ /* This is to force an update */
+ host->ops->set_clock(host, host->clock);
+
+ /*
+ * Spec says we should do both at the same time, but Ricoh
+ * controllers do not like that.
+ */
+ sdhci_do_reset(host, SDHCI_RESET_CMD);
+ sdhci_do_reset(host, SDHCI_RESET_DATA);
+
+ host->pending_reset = false;
+ }
+
+ /*
* Always unmap the data buffers if they were mapped by
* sdhci_prepare_data() whenever we finish with a request.
* This avoids leaking DMA mappings on error.
@@ -3059,35 +3090,6 @@ static bool sdhci_request_done(struct sd
}
}

- /*
- * The controller needs a reset of internal state machines
- * upon error conditions.
- */
- if (sdhci_needs_reset(host, mrq)) {
- /*
- * Do not finish until command and data lines are available for
- * reset. Note there can only be one other mrq, so it cannot
- * also be in mrqs_done, otherwise host->cmd and host->data_cmd
- * would both be null.
- */
- if (host->cmd || host->data_cmd) {
- spin_unlock_irqrestore(&host->lock, flags);
- return true;
- }
-
- /* Some controllers need this kick or reset won't work here */
- if (host->quirks & SDHCI_QUIRK_CLOCK_BEFORE_RESET)
- /* This is to force an update */
- host->ops->set_clock(host, host->clock);
-
- /* Spec says we should do both at the same time, but Ricoh
- controllers do not like that. */
- sdhci_do_reset(host, SDHCI_RESET_CMD);
- sdhci_do_reset(host, SDHCI_RESET_DATA);
-
- host->pending_reset = false;
- }
-
host->mrqs_done[i] = NULL;

spin_unlock_irqrestore(&host->lock, flags);