[Xen-devel] [PATCH v2 2/2] x86/mmcfg/drhd: Move acpi_mmcfg_init() call before calling acpi_parse_dmar()

[Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>]

pci_conf_read8() needs pci mmcfg mapping to work on multiple pci segments
system such as HPE Superdome-Flex.

Move acpi_mmcfg_init() call in acpi_boot_init() before calling
acpi_parse_dmar() so that when pci_conf_read8() is called in
acpi_parse_dev_scope(), we already have the mapping set up.

acpi_mmcfg_init() only setup mmcfg mapping and has some global variables
initialized so there is no hazard to move it ahead. Meanwhile from its
name, acpi_boot_init() is a proper place to call it.

The alternative is moving the acpi_parse_dev_scope() call to a later point
after acpi_mmcfg_init(). But acpi_parse_one_drhd(), acpi_parse_one_rmrr()
and acpi_parse_one_atsr() all called acpi_parse_dev_scope() as their main
job. Splitting those functions to two pieces looks less optimal and meaningless.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>
Tested-by: Gopalasetty, Manoj <manoj.gopalasetty@xxxxxxx>
---
 xen/arch/x86/acpi/boot.c |    2 ++
 xen/arch/x86/setup.c     |    2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/acpi/boot.c b/xen/arch/x86/acpi/boot.c
index 8e6c96d..e89c2e9 100644
--- a/xen/arch/x86/acpi/boot.c
+++ b/xen/arch/x86/acpi/boot.c
@@ -724,6 +724,8 @@ int __init acpi_boot_init(void)
 
        acpi_table_parse(ACPI_SIG_HPET, acpi_parse_hpet);
 
+       acpi_mmcfg_init();
+
        acpi_dmar_init();
 
        erst_init();
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index d5cc584..9d0cd3b 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1598,8 +1598,6 @@ void __init noreturn __start_xen(unsigned long mbi_p)
 
     vesa_mtrr_init();
 
-    acpi_mmcfg_init();
-
     early_msi_init();
 
     iommu_setup();    /* setup iommu if available */
-- 
1.7.3

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