hw/nvme: Validate PMR memory size

Per the PCI spec 3.0, in section 6.2.5.1, "Address Maps":

  A 32-bit register can be implemented to support a single
  memory size that is a power of 2 from 16 bytes to 2 GB.

Add a check in nvme_init_pmr(), returning an error if the
PMR region size is too small; and update the QTest.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>

hw/nvme/ctrl.c

@@ -8814,10 +8814,15 @@ static void nvme_init_cmb(NvmeCtrl *n, PCIDevice *pci_dev)
     }
 }
 
-static void nvme_init_pmr(NvmeCtrl *n, PCIDevice *pci_dev)
+static bool nvme_init_pmr(NvmeCtrl *n, PCIDevice *pci_dev, Error **errp)
 {
     uint32_t pmrcap = ldl_le_p(&n->bar.pmrcap);
 
+    if (memory_region_size(&n->pmr.dev->mr) < 16) {
+        error_setg(errp, "PMR device must have at least 16 bytes");
+        return false;
+    }
+
     NVME_PMRCAP_SET_RDS(pmrcap, 1);
     NVME_PMRCAP_SET_WDS(pmrcap, 1);
     NVME_PMRCAP_SET_BIR(pmrcap, NVME_PMR_BIR);
@@ -8832,6 +8837,8 @@ static void nvme_init_pmr(NvmeCtrl *n, PCIDevice *pci_dev)
                      PCI_BASE_ADDRESS_MEM_PREFETCH, &n->pmr.dev->mr);
 
     memory_region_set_enabled(&n->pmr.dev->mr, false);
+
+    return true;
 }
 
 static uint64_t nvme_mbar_size(unsigned total_queues, unsigned total_irqs,
@@ -9050,7 +9057,9 @@ static bool nvme_init_pci(NvmeCtrl *n, PCIDevice *pci_dev, Error **errp)
     }
 
     if (n->pmr.dev) {
-        nvme_init_pmr(n, pci_dev);
+        if (!nvme_init_pmr(n, pci_dev, errp)) {
+            return false;
+        }
     }
 
     return true;

tests/qtest/nvme-test.c

@@ -149,7 +149,7 @@ static void nvme_register_nodes(void)
         .before_cmd_line = "-drive id=drv0,if=none,file=null-co://,"
                            "file.read-zeroes=on,format=raw "
                            "-object memory-backend-ram,id=pmr0,"
-                           "share=on,size=8",
+                           "share=on,size=16",
     };
 
     add_qpci_address(&opts, &(QPCIAddress) { .devfn = QPCI_DEVFN(4, 0) });