pcie: introduce pcie_sltctl_powered_off() helper

In pcie_cap_slot_write_config() we check for PCI_EXP_SLTCTL_PWR_OFF in
a bad form. We should distinguish PCI_EXP_SLTCTL_PWR which is a "mask"
and PCI_EXP_SLTCTL_PWR_OFF which is value for that mask.

Better code is in pcie_cap_slot_unplug_request_cb() and in
pcie_cap_update_power(). Let's use same pattern everywhere. To simplify
things add also a helper.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Anton Kuchin <antonkuchin@yandex-team.ru>
Message-Id: <20230216180356.156832-12-vsementsov@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/pci/pcie.c

@@ -39,6 +39,11 @@
 #define PCIE_DEV_PRINTF(dev, fmt, ...)                                  \
     PCIE_DPRINTF("%s:%x "fmt, (dev)->name, (dev)->devfn, ## __VA_ARGS__)
 
+static bool pcie_sltctl_powered_off(uint16_t sltctl)
+{
+    return (sltctl & PCI_EXP_SLTCTL_PCC) == PCI_EXP_SLTCTL_PWR_OFF
+        && (sltctl & PCI_EXP_SLTCTL_PIC) == PCI_EXP_SLTCTL_PWR_IND_OFF;
+}
 
 /***************************************************************************
  * pci express capability helper functions
@@ -395,6 +400,7 @@ static void pcie_cap_update_power(PCIDevice *hotplug_dev)
 
     if (sltcap & PCI_EXP_SLTCAP_PCP) {
         power = (sltctl & PCI_EXP_SLTCTL_PCC) == PCI_EXP_SLTCTL_PWR_ON;
+        /* Don't we need to check also (sltctl & PCI_EXP_SLTCTL_PIC) ? */
     }
 
     pci_for_each_device(sec_bus, pci_bus_num(sec_bus),
@@ -579,8 +585,7 @@ void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
         return;
     }
 
-    if (((sltctl & PCI_EXP_SLTCTL_PIC) == PCI_EXP_SLTCTL_PWR_IND_OFF) &&
-        ((sltctl & PCI_EXP_SLTCTL_PCC) == PCI_EXP_SLTCTL_PWR_OFF)) {
+    if (pcie_sltctl_powered_off(sltctl)) {
         /* slot is powered off -> unplug without round-trip to the guest */
         pcie_cap_slot_do_unplug(hotplug_pdev);
         hotplug_event_notify(hotplug_pdev);
@@ -770,10 +775,9 @@ void pcie_cap_slot_write_config(PCIDevice *dev,
      * this is a work around for guests that overwrite
      * control of powered off slots before powering them on.
      */
-    if ((sltsta & PCI_EXP_SLTSTA_PDS) && (val & PCI_EXP_SLTCTL_PCC) &&
-        (val & PCI_EXP_SLTCTL_PIC) == PCI_EXP_SLTCTL_PWR_IND_OFF &&
-        (!(old_slt_ctl & PCI_EXP_SLTCTL_PCC) ||
-        (old_slt_ctl & PCI_EXP_SLTCTL_PIC) != PCI_EXP_SLTCTL_PWR_IND_OFF)) {
+    if ((sltsta & PCI_EXP_SLTSTA_PDS) && pcie_sltctl_powered_off(val) &&
+        !pcie_sltctl_powered_off(old_slt_ctl))
+    {
         pcie_cap_slot_do_unplug(dev);
     }
     pcie_cap_update_power(dev);