Re: [RFC PATCH v2 05/22] xen-platform-pci: allow its creation with XEN_EMULATE mode

[Paul Durrant]

On 09/12/2022 09:55, David Woodhouse wrote:
From: Joao Martins <joao.m.mart...@oracle.com>
The only thing we need to handle on KVM side is to change the
pfn from R/W to R/O.

Signed-off-by: Joao Martins <joao.m.mart...@oracle.com>
Signed-off-by: David Woodhouse <d...@amazon.co.uk>
---
  hw/i386/xen/xen_platform.c | 11 ++++-------
  1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/hw/i386/xen/xen_platform.c b/hw/i386/xen/xen_platform.c
index a64265cca0..914619d140 100644
--- a/hw/i386/xen/xen_platform.c
+++ b/hw/i386/xen/xen_platform.c
@@ -271,7 +271,10 @@ static void platform_fixed_ioport_writeb(void *opaque, 
uint32_t addr, uint32_t v
      case 0: /* Platform flags */ {
          hvmmem_type_t mem_type = (val & PFFLAG_ROM_LOCK) ?
              HVMMEM_ram_ro : HVMMEM_ram_rw;
-        if (xen_set_mem_type(xen_domid, mem_type, 0xc0, 0x40)) {
+        if (xen_mode == XEN_EMULATE) {
+            /* XXX */
+            s->flags = val & PFFLAG_ROM_LOCK;
+        } else if (xen_set_mem_type(xen_domid, mem_type, 0xc0, 0x40)) {
              DPRINTF("unable to change ro/rw state of ROM memory area!\n");
          } else {
              s->flags = val & PFFLAG_ROM_LOCK;

Surely this would cleaner as:

if (xen_mode != XEN_EMULATE && xen_set_mem_type(xen_domid, mem_type, 
0xc0, 0x40))
    DPRINTF("unable to change ro/rw state of ROM memory area!\n");
else
    s->flags = val & PFFLAG_ROM_LOCK;

?

  Paul

@@ -496,12 +499,6 @@ static void xen_platform_realize(PCIDevice *dev, Error 
**errp)
      PCIXenPlatformState *d = XEN_PLATFORM(dev);
      uint8_t *pci_conf;
  
-    /* Device will crash on reset if xen is not initialized */
-    if (!xen_enabled()) {
-        error_setg(errp, "xen-platform device requires the Xen accelerator");
-        return;
-    }
-
      pci_conf = dev->config;
  
      pci_set_word(pci_conf + PCI_COMMAND, PCI_COMMAND_IO | PCI_COMMAND_MEMORY);