[Qemu-devel] [PATCH] Enable NVMe start controller for Windows guest.

[Qemu-devel] [PATCH] Enable NVMe start controller for Windows guest.

[Daniel Stekloff]

Windows seems to send two separate calls to NVMe controller configuration. The
first sends configuration info and the second the enable bit. I couldn't
enable the Windows 8.1 in-box NVMe driver with base Qemu. I made the
following change to store the configuration data and then handle enable and
NVMe driver works on Windows 8.1.

I am not a Windows expert and I'm not entirely sure this is the correct
approach. I'm offering it for anyone who wishes to use NVMe on Windows 8.1
using Qemu.

I have tested this change with Linux and Windows guests with NVMe devices.

Signed-off-by: Daniel Stekloff <dan@wendan.org>

---
 hw/block/nvme.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 1e07166..ad988d7 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -615,6 +615,13 @@ static void nvme_write_bar(NvmeCtrl *n, hwaddr offset, uint64_t data,
         n->bar.intmc = n->bar.intms;
         break;
     case 0x14:
+        /* Windows first sends data, then sends enable bit */
+        if (!NVME_CC_EN(data) && !NVME_CC_EN(n->bar.cc) &&
+            !NVME_CC_SHN(data) && !NVME_CC_SHN(n->bar.cc))
+        {
+            n->bar.cc = data;
+        }
+
         if (NVME_CC_EN(data) && !NVME_CC_EN(n->bar.cc)) {
             n->bar.cc = data;
             if (nvme_start_ctrl(n)) {
-- 
1.9.1

Re: [Qemu-devel] [PATCH] Enable NVMe start controller for Windows guest.

[Keith Busch]

On Fri, 24 Apr 2015, Daniel Stekloff wrote:
> Windows seems to send two separate calls to NVMe controller configuration. The
> first sends configuration info and the second the enable bit. I couldn't
> enable the Windows 8.1 in-box NVMe driver with base Qemu. I made the
> following change to store the configuration data and then handle enable and
> NVMe driver works on Windows 8.1.

Hm, Microsoft's driver must be issuing MMIO reads to mask in the enable
bit rather than keep the state known. Sounds odd, but thanks for the fix.

Acked-by: Keith Busch <keith.busch@intel.com>

Re: [Qemu-devel] [PATCH] Enable NVMe start controller for Windows guest.

[Kevin Wolf]

[Cc: qemu-block]

Am 24.04.2015 um 21:19 hat Keith Busch geschrieben:
> On Fri, 24 Apr 2015, Daniel Stekloff wrote:
> >Windows seems to send two separate calls to NVMe controller configuration. The
> >first sends configuration info and the second the enable bit. I couldn't
> >enable the Windows 8.1 in-box NVMe driver with base Qemu. I made the
> >following change to store the configuration data and then handle enable and
> >NVMe driver works on Windows 8.1.
> 
> Hm, Microsoft's driver must be issuing MMIO reads to mask in the enable
> bit rather than keep the state known. Sounds odd, but thanks for the fix.
> 
> Acked-by: Keith Busch <keith.busch@intel.com>

Thanks, applied to the block branch.

Kevin