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Date: Tue, 15 Feb 2022 21:20:32 +0100
From: Hans de Goede <hdegoede@...hat.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: "Rafael J . Wysocki" <rjw@...ysocki.net>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
"H . Peter Anvin" <hpa@...or.com>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
Krzysztof Wilczyński <kw@...ux.com>,
Myron Stowe <myron.stowe@...hat.com>,
Juha-Pekka Heikkila <juhapekka.heikkila@...il.com>,
Benoit Grégoire <benoitg@...us.ca>,
Hui Wang <hui.wang@...onical.com>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Linux PCI <linux-pci@...r.kernel.org>,
the arch/x86 maintainers <x86@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC 0/2] x86/PCI: Ignore EFI memmap MMIO entries
Hi,
On 2/15/22 18:20, Rafael J. Wysocki wrote:
> On Tue, Feb 15, 2022 at 5:12 PM Hans de Goede <hdegoede@...hat.com> wrote:
>>
>> Hi All,
>>
>> On 2/14/22 16:17, Hans de Goede wrote:
>>> Hi All,
>>>
>>> Here is a new attempt at fixing the issue where on some laptops
>>> there are EFI memmap MMIO entries covering the entire PCI bridge
>>> mem window, causing Linux to be unable to find free space to
>>> assign to unassigned BARs.
>>>
>>> This is marked as RFC atm because I'm waiting for feedback from
>>> testers.
>>
>> Unfortunately the troublesome 0xdfa00000-0xdfa0ffff region on
>> the Lenovo X1 carbon gen 2 is marked as MMIO by the EFI memmap,
>> so the approach from this series won't work.
>>
>> Interestingly enough this RFC series does seem to help to fix
>> the suspend/resume on this x1c2, since for some reason merely
>> splitting the original:
>>
>> BIOS-e820: [mem 0x00000000dceff000-0x00000000dfa0ffff] reserved
>>
>> range into:
>>
>> BIOS-e820: [mem 0x00000000dceff000-0x00000000df9fffff] reserved
>> BIOS-e820: [mem 0x00000000dfa00000-0x00000000dfa0ffff] MMIO
>>
>> causes the PCI resource allocation code to pick slightly
>> different resources avoiding the troublesome overlap, see:
>> https://bugzilla.redhat.com/show_bug.cgi?id=2029207
>> for logs.
>>
>> But I don't think we should rely in this, since from a
>> arch_remove_reservations() pov the troublesome overlap area
>> which is now marked as MMIO is fair game for PCI bars with
>> the change to allow MMIO areas for PCI bars, so things seem
>> to mostly work by sheer luck after this RFC series.
>>
>> So now I have yet another plan to fix this (see below) I'll get
>> that tested and assuming it works post that as a proper patch.
>>
>> Regards,
>>
>> Hans
>>
>>
>>
>> diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
>> index 490411dba438..573e1323f490 100644
>> --- a/arch/x86/include/asm/pci_x86.h
>> +++ b/arch/x86/include/asm/pci_x86.h
>> @@ -64,6 +64,8 @@ void pcibios_scan_specific_bus(int busn);
>>
>> /* pci-irq.c */
>>
>> +struct pci_dev;
>> +
>> struct irq_info {
>> u8 bus, devfn; /* Bus, device and function */
>> struct {
>> @@ -232,3 +234,9 @@ static inline void mmio_config_writel(void __iomem *pos, u32 val)
>> # define x86_default_pci_init_irq NULL
>> # define x86_default_pci_fixup_irqs NULL
>> #endif
>> +
>> +#if defined CONFIG_PCI && defined CONFIG_ACPI
>> +extern bool pci_use_e820;
>> +#else
>> +#define pci_use_e820 true
>> +#endif
>> diff --git a/arch/x86/kernel/resource.c b/arch/x86/kernel/resource.c
>> index 9b9fb7882c20..e8dc9bc327bd 100644
>> --- a/arch/x86/kernel/resource.c
>> +++ b/arch/x86/kernel/resource.c
>> @@ -1,6 +1,7 @@
>> // SPDX-License-Identifier: GPL-2.0
>> #include <linux/ioport.h>
>> #include <asm/e820/api.h>
>> +#include <asm/pci_x86.h>
>>
>> static void resource_clip(struct resource *res, resource_size_t start,
>> resource_size_t end)
>> @@ -28,6 +29,9 @@ static void remove_e820_regions(struct resource *avail)
>> int i;
>> struct e820_entry *entry;
>>
>> + if (!pci_use_e820)
>> + return;
>> +
>> for (i = 0; i < e820_table->nr_entries; i++) {
>> entry = &e820_table->entries[i];
>>
>> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
>> index 052f1d78a562..7167934819b3 100644
>> --- a/arch/x86/pci/acpi.c
>> +++ b/arch/x86/pci/acpi.c
>> @@ -1,4 +1,5 @@
>> // SPDX-License-Identifier: GPL-2.0
>> +#include <linux/efi.h>
>> #include <linux/pci.h>
>> #include <linux/acpi.h>
>> #include <linux/init.h>
>> @@ -21,6 +22,7 @@ struct pci_root_info {
>>
>> static bool pci_use_crs = true;
>> static bool pci_ignore_seg;
>> +bool pci_use_e820 = true;
>>
>> static int __init set_use_crs(const struct dmi_system_id *id)
>> {
>> @@ -291,6 +293,28 @@ static bool resource_is_pcicfg_ioport(struct resource *res)
>> res->start == 0xCF8 && res->end == 0xCFF;
>> }
>>
>> +static bool resource_matches_efi_mmio_region(const struct resource *res)
>
> I would call this resource_is_efi_mmio() FWIW.
Ack, fixed in my local tree.
>
>> +{
>> + unsigned long long start, end;
>> + efi_memory_desc_t *md;
>> +
>> + if (!efi_enabled(EFI_MEMMAP))
>> + return false;
>> +
>> + for_each_efi_memory_desc(md) {
>> + if (md->type != EFI_MEMORY_MAPPED_IO)
>> + continue;
>> +
>> + start = md->phys_addr;
>> + end = start + (md->num_pages << EFI_PAGE_SHIFT) - 1;
>> +
>> + if (res->start >= start && res->end <= end)
>> + return true;
>> + }
>> +
>> + return false;
>> +}
>> +
>> static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci)
>> {
>> struct acpi_device *device = ci->bridge;
>> @@ -300,9 +324,16 @@ static int pci_acpi_root_prepare_resources(struct acpi_pci_root_info *ci)
>>
>> status = acpi_pci_probe_root_resources(ci);
>> if (pci_use_crs) {
>> - resource_list_for_each_entry_safe(entry, tmp, &ci->resources)
>> + resource_list_for_each_entry_safe(entry, tmp, &ci->resources) {
>> if (resource_is_pcicfg_ioport(entry->res))
>> resource_list_destroy_entry(entry);
>> + if (resource_matches_efi_mmio_region(entry->res)) {
>
> I would add a pci_use_e820 check to this.
I'm not sure about that, this code path should run only once per bridge and if multiple
bridges are affected then it would be good to have this info level message for all of
them.
OTOH I guess we only expect this to affect the main window for the root PCI bridge
and then the windows for any bridges below that will also automatically fit within
the same EFI memmap entry, resulting in what is more or less a false-positive
logging of the message.
I've build a test-kernel for both the reporter of the original touchpad (i2c-controller
PCI bar assignment) issue as well as the suspend/resume regression on the x1c2 reporter
to test, which does not have your suggestion. I'll check the logs there and if there
are indeed duplicate log messages I'll implement your suggestion.
Regards,
Hans
>
>> + dev_info(&device->dev,
>> + "host bridge window %pR is marked by EFI as MMIO\n",
>> + entry->res);
>> + pci_use_e820 = false;
>> + }
>> + }
>> return status;
>> }
>
> Overall, it looks reasonable to me.
>
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