[PATCH] hw/cxl: Fix msix_notify: Assertion `vector < dev->msix_entries_nr`

[Li Zhijian via]

This assertion always happens when we sanitize the CXL memory device.
$ echo 1 > /sys/bus/cxl/devices/mem0/security/sanitize

It is incorrect to register an MSIX number beyond the device's capability.

Expand the device's MSIX to 10 and introduce the `request_msix_number()`
helper function to dynamically request an available MSIX number.

Fixes: 43efb0bfad2b ("hw/cxl/mbox: Wire up interrupts for background 
completion")
Signed-off-by: Li Zhijian <lizhij...@fujitsu.com>
---
 hw/cxl/cxl-device-utils.c   |  3 ++-
 hw/mem/cxl_type3.c          | 15 ++++++++++++++-
 include/hw/cxl/cxl_device.h |  2 ++
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/hw/cxl/cxl-device-utils.c b/hw/cxl/cxl-device-utils.c
index 035d034f6d..8e52af6813 100644
--- a/hw/cxl/cxl-device-utils.c
+++ b/hw/cxl/cxl-device-utils.c
@@ -354,8 +354,9 @@ static void device_reg_init_common(CXLDeviceState 
*cxl_dstate)
 
 static void mailbox_reg_init_common(CXLDeviceState *cxl_dstate)
 {
-    const uint8_t msi_n = 9;
+    uint8_t msi_n = cxl_request_msi_number();
 
+    assert(msi_n > 0);
     /* 2048 payload size */
     ARRAY_FIELD_DP32(cxl_dstate->mbox_reg_state32, CXL_DEV_MAILBOX_CAP,
                      PAYLOAD_SIZE, CXL_MAILBOX_PAYLOAD_SHIFT);
diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c
index 5cf754b38f..dbb1368736 100644
--- a/hw/mem/cxl_type3.c
+++ b/hw/mem/cxl_type3.c
@@ -835,6 +835,19 @@ static DOEProtocol doe_cdat_prot[] = {
     { }
 };
 
+#define CT3_MSIX_NUM 10
+unsigned short cxl_request_msi_number(void)
+{
+    const unsigned short start = 6;
+    static unsigned short next = start;
+
+    if (next + 1 >= CT3_MSIX_NUM) {
+        return -1;
+    }
+
+    return ++next;
+}
+
 static void ct3_realize(PCIDevice *pci_dev, Error **errp)
 {
     ERRP_GUARD();
@@ -843,7 +856,7 @@ static void ct3_realize(PCIDevice *pci_dev, Error **errp)
     ComponentRegisters *regs = &cxl_cstate->crb;
     MemoryRegion *mr = &regs->component_registers;
     uint8_t *pci_conf = pci_dev->config;
-    unsigned short msix_num = 6;
+    unsigned short msix_num = CT3_MSIX_NUM;
     int i, rc;
     uint16_t count;
 
diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
index 561b375dc8..622265f50e 100644
--- a/include/hw/cxl/cxl_device.h
+++ b/include/hw/cxl/cxl_device.h
@@ -680,4 +680,6 @@ void ct3_clear_region_block_backed(CXLType3Dev *ct3d, 
uint64_t dpa,
                                    uint64_t len);
 bool ct3_test_region_block_backed(CXLType3Dev *ct3d, uint64_t dpa,
                                   uint64_t len);
+unsigned short cxl_request_msi_number(void);
+
 #endif
-- 
2.41.0