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x86/hyperv: Fix the detection of E820_TYPE_PRAM in a Gen2 VM
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 <ssengar@linux.microsoft.com> Signed-off-by: Dexuan Cui <decui@microsoft.com> Signed-off-by: Wei Liu <wei.liu@kernel.org> Message-ID: <1699691867-9827-1-git-send-email-ssengar@linux.microsoft.com>
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@ -15,6 +15,7 @@
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#include <linux/io.h>
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#include <asm/apic.h>
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#include <asm/desc.h>
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#include <asm/e820/api.h>
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#include <asm/sev.h>
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#include <asm/ibt.h>
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#include <asm/hypervisor.h>
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@ -286,15 +287,31 @@ static int hv_cpu_die(unsigned int cpu)
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static int __init hv_pci_init(void)
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{
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int gen2vm = efi_enabled(EFI_BOOT);
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bool gen2vm = efi_enabled(EFI_BOOT);
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/*
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* For Generation-2 VM, we exit from pci_arch_init() by returning 0.
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* The purpose is to suppress the harmless warning:
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* A Generation-2 VM doesn't support legacy PCI/PCIe, so both
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* raw_pci_ops and raw_pci_ext_ops are NULL, and pci_subsys_init() ->
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* pcibios_init() doesn't call pcibios_resource_survey() ->
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* e820__reserve_resources_late(); as a result, any emulated persistent
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* memory of E820_TYPE_PRAM (12) via the kernel parameter
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* memmap=nn[KMG]!ss is not added into iomem_resource and hence can't be
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* detected by register_e820_pmem(). Fix this by directly calling
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* e820__reserve_resources_late() here: e820__reserve_resources_late()
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* depends on e820__reserve_resources(), which has been called earlier
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* from setup_arch(). Note: e820__reserve_resources_late() also adds
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* any memory of E820_TYPE_PMEM (7) into iomem_resource, and
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* acpi_nfit_register_region() -> acpi_nfit_insert_resource() ->
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* region_intersects() returns REGION_INTERSECTS, so the memory of
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* E820_TYPE_PMEM won't get added twice.
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*
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* We return 0 here so that pci_arch_init() won't print the warning:
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* "PCI: Fatal: No config space access function found"
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*/
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if (gen2vm)
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if (gen2vm) {
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e820__reserve_resources_late();
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return 0;
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}
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/* For Generation-1 VM, we'll proceed in pci_arch_init(). */
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return 1;
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