From 54d8c1d3261dfb8be84ffc17cf94fa231c9d88d4 Mon Sep 17 00:00:00 2001 From: Saurabh Sengar Date: Sat, 11 Nov 2023 00:37:47 -0800 Subject: [PATCH] x86/hyperv: Fix the detection of E820_TYPE_PRAM in a Gen2 VM [ Upstream commit 7e8037b099c0bbe8f2109dc452dbcab8d400fc53 ] A Gen2 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() in hv_pci_init(), which is called from arch_initcall(pci_arch_init). It's ok to move a Gen2 VM's e820__reserve_resources_late() from subsys_initcall(pci_subsys_init) to arch_initcall(pci_arch_init) because the code in-between doesn't depend on the E820 resources. e820__reserve_resources_late() depends on e820__reserve_resources(), which has been called earlier from setup_arch(). For a Gen-2 VM, the new hv_pci_init() 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. Changed the local variable "int gen2vm" to "bool gen2vm". Signed-off-by: Saurabh Sengar Signed-off-by: Dexuan Cui Signed-off-by: Wei Liu Message-ID: <1699691867-9827-1-git-send-email-ssengar@linux.microsoft.com> Signed-off-by: Sasha Levin --- arch/x86/hyperv/hv_init.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 21556ad..8f3a4d1 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -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; -- 2.7.4