On Thu, Aug 10, 2023 at 10:31:37PM -0700, Dexuan Cui wrote: > 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 <[email protected]> > Signed-off-by: Dexuan Cui <[email protected]> > --- > 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 b004370d3b01..6b22d49aee7b 100644 > --- a/arch/x86/hyperv/hv_init.c > +++ b/arch/x86/hyperv/hv_init.c > @@ -13,6 +13,7 @@ > #include <linux/io.h> > #include <asm/apic.h> > #include <asm/desc.h> > +#include <asm/e820/api.h> > #include <asm/sev.h> > #include <asm/hypervisor.h> > #include <asm/hyperv-tlfs.h> > @@ -282,15 +283,31 @@ 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; > + }
Kind reminder to review this. - Saurabh > > /* For Generation-1 VM, we'll proceed in pci_arch_init(). */ > return 1; > > -- > 2.25.1 >
