[Xen-devel] [PATCH for-2.10 v2 1/2] hw/acpi: Call acpi_set_pci_info when no ACPI tables needed

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

To do PCI passthrough with Xen, the property acpi-pcihp-bsel needs to be
set, but this was done only when ACPI tables are built which is not
needed for a Xen guest. The need for the property starts with commit
"pc: pcihp: avoid adding ACPI_PCIHP_PROP_BSEL twice"
(f0c9d64a68b776374ec4732424a3e27753ce37b6).

Set pci info before checking for the needs to build ACPI tables.

Assign bsel=0 property only to the root bus on Xen as there is no
support in the Xen ACPI tables for a different value.

Reported-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

---
Changes in V2:
  - check for acpi_enabled before calling acpi_set_pci_info.
  - set the property on the root bus only.

This patch would be a canditade to backport to 2.9.

CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Bruce Rogers <brogers@xxxxxxxx>
---
 hw/i386/acpi-build.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 98dd424678..c0483b96cf 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -46,6 +46,7 @@
 #include "sysemu/tpm_backend.h"
 #include "hw/timer/mc146818rtc_regs.h"
 #include "sysemu/numa.h"
+#include "hw/xen/xen.h"
 
 /* Supported chipsets: */
 #include "hw/acpi/piix4.h"
@@ -518,8 +519,13 @@ static void acpi_set_pci_info(void)
     unsigned bsel_alloc = ACPI_PCIHP_BSEL_DEFAULT;
 
     if (bus) {
-        /* Scan all PCI buses. Set property to enable acpi based hotplug. */
-        pci_for_each_bus_depth_first(bus, acpi_set_bsel, NULL, &bsel_alloc);
+        if (xen_enabled()) {
+            /* Assign BSEL property to root bus only. */
+            acpi_set_bsel(bus, &bsel_alloc);
+        } else {
+            /* Scan all PCI buses. Set property to enable acpi based hotplug. 
*/
+            pci_for_each_bus_depth_first(bus, acpi_set_bsel, NULL, 
&bsel_alloc);
+        }
     }
 }
 
@@ -2871,6 +2877,14 @@ void acpi_setup(void)
     AcpiBuildState *build_state;
     Object *vmgenid_dev;
 
+    if (!acpi_enabled) {
+        ACPI_BUILD_DPRINTF("ACPI disabled. Bailing out.\n");
+        return;
+    }
+
+    /* Assign BSEL property on hotpluggable PCI buses. */
+    acpi_set_pci_info();
+
     if (!pcms->fw_cfg) {
         ACPI_BUILD_DPRINTF("No fw cfg. Bailing out.\n");
         return;
@@ -2881,15 +2895,8 @@ void acpi_setup(void)
         return;
     }
 
-    if (!acpi_enabled) {
-        ACPI_BUILD_DPRINTF("ACPI disabled. Bailing out.\n");
-        return;
-    }
-
     build_state = g_malloc0(sizeof *build_state);
 
-    acpi_set_pci_info();
-
     acpi_build_tables_init(&tables);
     acpi_build(&tables, MACHINE(pcms));
 
-- 
Anthony PERARD


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