[PATCH] hw/sd/sdhci: Report error when guest access protected registers

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

The SDHC_SYSAD and SDHC_BLKSIZE can not be accessed while a
transaction is in progress, see 'SD Host Controller Simplified
Specification'

  1.5) SD Command Generation

  The Host Driver should not read the SDMA System Address, Block
  Size and Block Count registers during a data transaction unless
  the transfer is stopped because the value is changing and not
  stable.

Report guest intents as errors.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
Based-on: <1613447214-81951-1-git-send-email-bmeng.cn@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 hw/sd/sdhci.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/hw/sd/sdhci.c b/hw/sd/sdhci.c
index 5b8678110b0..98928c18542 100644
--- a/hw/sd/sdhci.c
+++ b/hw/sd/sdhci.c
@@ -1136,6 +1136,10 @@ sdhci_write(void *opaque, hwaddr offset, uint64_t val, unsigned size)
                     sdhci_sdma_transfer_single_block(s);
                 }
             }
+        } else {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "%s: Transfer already in progress,"
+                          " can not update SYSAD", __func__);
         }
         break;
     case SDHC_BLKSIZE:
@@ -1163,8 +1167,11 @@ sdhci_write(void *opaque, hwaddr offset, uint64_t val, unsigned size)
             if (blksize != s->blksize) {
                 s->data_count = 0;
             }
+        } else {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "%s: Transfer already in progress,"
+                          " can not update BLKSIZE", __func__);
         }
-
         break;
     case SDHC_ARGUMENT:
         MASKED_WRITE(s->argument, mask, value);
-- 
2.26.2