x86/hyperv: Fix the detection of E820_TYPE_PRAM in a Gen2 VM

[platform/kernel/linux-starfive.git] / arch / x86 / hyperv / hv_init.c

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 21556ad..8f3a4d1 100644 (file)
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -15,6 +15,7 @@
 #include <linux/io.h>
 #include <asm/apic.h>
 #include <asm/desc.h>
+#include <asm/e820/api.h>
 #include <asm/sev.h>
 #include <asm/ibt.h>
 #include <asm/hypervisor.h>
@@ -286,15 +287,31 @@ static int hv_cpu_die(unsigned int cpu)
 
 static int __init hv_pci_init(void)
 {
-       int gen2vm = efi_enabled(EFI_BOOT);
+       bool gen2vm = efi_enabled(EFI_BOOT);
 
        /*
-        * For Generation-2 VM, we exit from pci_arch_init() by returning 0.
-        * The purpose is to suppress the harmless warning:
+        * A Generation-2 VM doesn't support legacy PCI/PCIe, so both
+        * raw_pci_ops and raw_pci_ext_ops are NULL, and pci_subsys_init() ->
+        * pcibios_init() doesn't call pcibios_resource_survey() ->
+        * e820__reserve_resources_late(); as a result, any emulated persistent
+        * memory of E820_TYPE_PRAM (12) via the kernel parameter
+        * memmap=nn[KMG]!ss is not added into iomem_resource and hence can't be
+        * detected by register_e820_pmem(). Fix this by directly calling
+        * e820__reserve_resources_late() here: e820__reserve_resources_late()
+        * depends on e820__reserve_resources(), which has been called earlier
+        * from setup_arch(). Note: e820__reserve_resources_late() also adds
+        * any memory of E820_TYPE_PMEM (7) into iomem_resource, and
+        * acpi_nfit_register_region() -> acpi_nfit_insert_resource() ->
+        * region_intersects() returns REGION_INTERSECTS, so the memory of
+        * E820_TYPE_PMEM won't get added twice.
+        *
+        * We return 0 here so that pci_arch_init() won't print the warning:
         * "PCI: Fatal: No config space access function found"
         */
-       if (gen2vm)
+       if (gen2vm) {
+               e820__reserve_resources_late();
                return 0;
+       }
 
        /* For Generation-1 VM, we'll proceed in pci_arch_init().  */
        return 1;