[PATCH v2] hw/nvme: clean up CC register write logic

[Klaus Jensen <its@irrelevant.dk>]

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

The SRIOV series exposed an issued with how CC register writes are
handled and how CSTS is set in response to that. Specifically, after
applying the SRIOV series, the controller could end up in a state with
CC.EN set to '1' but with CSTS.RDY cleared to '0', causing drivers to
expect CSTS.RDY to transition to '1' but timing out.

Clean this up.

Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
---
 hw/nvme/ctrl.c | 37 +++++++++++++++----------------------
 1 file changed, 15 insertions(+), 22 deletions(-)

diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index 658584d417fe..8b16b2b8febb 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -6190,8 +6190,12 @@ static void nvme_ctrl_reset(NvmeCtrl *n, NvmeResetType rst)
 
     if (pci_is_vf(pci_dev)) {
         sctrl = nvme_sctrl(n);
+
         stl_le_p(&n->bar.csts, sctrl->scs ? 0 : NVME_CSTS_FAILED);
     } else {
+        stl_le_p(&n->bar.intms, 0);
+        stl_le_p(&n->bar.intmc, 0);
+        stl_le_p(&n->bar.cc, 0);
         stl_le_p(&n->bar.csts, 0);
     }
 }
@@ -6405,20 +6409,21 @@ static void nvme_write_bar(NvmeCtrl *n, hwaddr offset, uint64_t data,
         nvme_irq_check(n);
         break;
     case NVME_REG_CC:
+        stl_le_p(&n->bar.cc, data);
+
         trace_pci_nvme_mmio_cfg(data & 0xffffffff);
 
-        /* Windows first sends data, then sends enable bit */
-        if (!NVME_CC_EN(data) && !NVME_CC_EN(cc) &&
-            !NVME_CC_SHN(data) && !NVME_CC_SHN(cc))
-        {
-            cc = data;
+        if (NVME_CC_SHN(data) && !(NVME_CC_SHN(cc))) {
+            trace_pci_nvme_mmio_shutdown_set();
+            nvme_ctrl_shutdown(n);
+            csts &= ~(CSTS_SHST_MASK << CSTS_SHST_SHIFT);
+            csts |= NVME_CSTS_SHST_COMPLETE;
+        } else if (!NVME_CC_SHN(data) && NVME_CC_SHN(cc)) {
+            trace_pci_nvme_mmio_shutdown_cleared();
+            csts &= ~(CSTS_SHST_MASK << CSTS_SHST_SHIFT);
         }
 
         if (NVME_CC_EN(data) && !NVME_CC_EN(cc)) {
-            cc = data;
-
-            /* flush CC since nvme_start_ctrl() needs the value */
-            stl_le_p(&n->bar.cc, cc);
             if (unlikely(nvme_start_ctrl(n))) {
                 trace_pci_nvme_err_startfail();
                 csts = NVME_CSTS_FAILED;
@@ -6429,22 +6434,10 @@ static void nvme_write_bar(NvmeCtrl *n, hwaddr offset, uint64_t data,
         } else if (!NVME_CC_EN(data) && NVME_CC_EN(cc)) {
             trace_pci_nvme_mmio_stopped();
             nvme_ctrl_reset(n, NVME_RESET_CONTROLLER);
-            cc = 0;
-            csts &= ~NVME_CSTS_READY;
-        }
 
-        if (NVME_CC_SHN(data) && !(NVME_CC_SHN(cc))) {
-            trace_pci_nvme_mmio_shutdown_set();
-            nvme_ctrl_shutdown(n);
-            cc = data;
-            csts |= NVME_CSTS_SHST_COMPLETE;
-        } else if (!NVME_CC_SHN(data) && NVME_CC_SHN(cc)) {
-            trace_pci_nvme_mmio_shutdown_cleared();
-            csts &= ~NVME_CSTS_SHST_COMPLETE;
-            cc = data;
+            break;
         }
 
-        stl_le_p(&n->bar.cc, cc);
         stl_le_p(&n->bar.csts, csts);
 
         break;
-- 
2.36.1