[PATCH v2 02/12] hw/block/nvme: fix 64 bit register hi/lo split writes

[Klaus Jensen]

From: Klaus Jensen <k.jensen@samsung.com>

64 bit registers like ASQ and ACQ should be writable by both a hi/lo 32
bit write combination as well as a plain 64 bit write. The spec does not
define ordering on the hi/lo split, but the code currently assumes that
the low order bits are written first. Additionally, the code does not
consider that another address might already have been written into the
register, causing the OR'ing to result in a bad address.

Fix this by explicitly overwriting only the low or high order bits for
32 bit writes.

Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
---
 hw/block/nvme.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index bd7e258c3c26..40b9f8ccfc0e 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -3781,19 +3781,21 @@ static void nvme_write_bar(NvmeCtrl *n, hwaddr offset, 
uint64_t data,
         trace_pci_nvme_mmio_aqattr(data & 0xffffffff);
         break;
     case 0x28:  /* ASQ */
-        n->bar.asq = data;
+        n->bar.asq = size == 8 ? data :
+            (n->bar.asq & ~0xffffffff) | (data & 0xffffffff);
         trace_pci_nvme_mmio_asqaddr(data);
         break;
     case 0x2c:  /* ASQ hi */
-        n->bar.asq |= data << 32;
+        n->bar.asq = (n->bar.asq & 0xffffffff) | (data << 32);
         trace_pci_nvme_mmio_asqaddr_hi(data, n->bar.asq);
         break;
     case 0x30:  /* ACQ */
         trace_pci_nvme_mmio_acqaddr(data);
-        n->bar.acq = data;
+        n->bar.acq = size == 8 ? data :
+            (n->bar.acq & ~0xffffffff) | (data & 0xffffffff);
         break;
     case 0x34:  /* ACQ hi */
-        n->bar.acq |= data << 32;
+        n->bar.acq = (n->bar.acq & 0xffffffff) | (data << 32);
         trace_pci_nvme_mmio_acqaddr_hi(data, n->bar.acq);
         break;
     case 0x38:  /* CMBLOC */
-- 
2.30.0