From: Wei Liu <wei.liu@kernel.org>
To: Saurabh Sengar <ssengar@linux.microsoft.com>
Cc: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org,
hpa@zytor.com, linux-hyperv@vger.kernel.org,
linux-kernel@vger.kernel.org, ssengar@microsoft.com
Subject: Re: [PATCH v2] x86/hyperv: Fix the detection of E820_TYPE_PRAM in a Gen2 VM
Date: Sun, 12 Nov 2023 22:50:48 +0000 [thread overview]
Message-ID: <ZVFWyO74GkJZCGR7@liuwe-devbox-debian-v2> (raw)
In-Reply-To: <1699691867-9827-1-git-send-email-ssengar@linux.microsoft.com>
On Sat, Nov 11, 2023 at 12:37:47AM -0800, Saurabh Sengar 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 <ssengar@linux.microsoft.com>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
Applied to hyperv-fixes. Thanks.
prev parent reply other threads:[~2023-11-12 22:50 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-11 8:37 [PATCH v2] x86/hyperv: Fix the detection of E820_TYPE_PRAM in a Gen2 VM Saurabh Sengar
2023-11-12 22:50 ` Wei Liu [this message]
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