Re: [RFCv3 1/1] platform/x86: Add virtual PMC driver used for S2Idle

From: Grzegorz Jaszczyk
Date: Thu Apr 06 2023 - 10:00:01 EST

+linux-acpi@xxxxxxxxxxxxxxx

Hi Hans, Rafael

czw., 6 kwi 2023 o 12:53 Hans de Goede <hdegoede@xxxxxxxxxx> napisał(a):
>
> Hi Grzegorz,
>
> On 3/29/23 14:33, Grzegorz Jaszczyk wrote:
> > Hi Hans,
> >
> > Do you think that this RFC is in good enough state to start the ACPI
> > ID registration process so after it will be completed we could land
> > this solution? Or maybe we could land it (of course if there are no
> > other remarks) even before and adjust if needed?
>
> I see from the links in the cover-letter that most of
> the previous discussion has happened on the linux-pm list
> and I believe that the linux-pm folks are in a better place
> to answer this question then I am.
>
> I have no objections against the suggested approach,
> but I don't really feel that it is my call to make if
> we should move forward with this.

Hans: I see and thank you for your feedback.

Rafael: Could you please comment above?

Thank you in advance,
Grzegorz

>
> Regards,
>
> Hans
>
>
>
> > pon., 13 lut 2023 o 11:11 Grzegorz Jaszczyk <jaz@xxxxxxxxxxxx> napisał(a):
> >>
> >> Virtual PMC driver is meant for the guest VMs for the S2Idle
> >> notification. Its purpose is to register S2Idle dev ops check handler,
> >> which will evaluate ACPI _DSM just before the guest enters S2Idle power
> >> state.
> >>
> >> This allows to trap on MMIO access done as a consequence of _DSM
> >> evaluation and therefore notify the VMM about the guest entering S2Idle
> >> state.
> >>
> >> Signed-off-by: Grzegorz Jaszczyk <jaz@xxxxxxxxxxxx>
> >> ---
> >> Changelog v1..v2:
> >> - Take advantage of acpi_s2idle_dev_ops's check() instead of notify()
> >>
> >> Changelog v2..v3:
> >> - Add MODULE_LICENSE
> >> - Remove "amd" prefixes
> >> - Be more verbose in VIRT_PMC config description and make it
> >> HYPERVISOR_GUEST dependent
> >> - Add extra check ensuring that DSM method supports ACPI_VIRT_PMC_NOTIFY function
> >> ---
> >> drivers/platform/x86/Kconfig | 7 +++
> >> drivers/platform/x86/Makefile | 3 ++
> >> drivers/platform/x86/virt_pmc.c | 83 +++++++++++++++++++++++++++++++++
> >> 3 files changed, 93 insertions(+)
> >> create mode 100644 drivers/platform/x86/virt_pmc.c
> >>
> >> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> >> index 5692385e2d26..837ce201b68b 100644
> >> --- a/drivers/platform/x86/Kconfig
> >> +++ b/drivers/platform/x86/Kconfig
> >> @@ -1099,6 +1099,13 @@ config WINMATE_FM07_KEYS
> >> buttons below the display. This module adds an input device
> >> that delivers key events when these buttons are pressed.
> >>
> >> +config VIRT_PMC
> >> + tristate "Virtual Power Management Controller"
> >> + depends on ACPI && SUSPEND && HYPERVISOR_GUEST
> >> + help
> >> + The Virtual PMC driver is meant for the guest VMs and its main
> >> + purpose is to notify about guest entering s2idle state.
> >> +
> >> endif # X86_PLATFORM_DEVICES
> >>
> >> config P2SB
> >> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> >> index 1d3d1b02541b..c4d3056cf4ea 100644
> >> --- a/drivers/platform/x86/Makefile
> >> +++ b/drivers/platform/x86/Makefile
> >> @@ -129,6 +129,9 @@ obj-$(CONFIG_INTEL_SCU_WDT) += intel_scu_wdt.o
> >> obj-$(CONFIG_INTEL_SCU_IPC_UTIL) += intel_scu_ipcutil.o
> >> obj-$(CONFIG_X86_INTEL_LPSS) += pmc_atom.o
> >>
> >> +# Virtual PMC
> >> +obj-$(CONFIG_VIRT_PMC) += virt_pmc.o
> >> +
> >> # Siemens Simatic Industrial PCs
> >> obj-$(CONFIG_SIEMENS_SIMATIC_IPC) += simatic-ipc.o
> >>
> >> diff --git a/drivers/platform/x86/virt_pmc.c b/drivers/platform/x86/virt_pmc.c
> >> new file mode 100644
> >> index 000000000000..a5966bb9048f
> >> --- /dev/null
> >> +++ b/drivers/platform/x86/virt_pmc.c
> >> @@ -0,0 +1,83 @@
> >> +// SPDX-License-Identifier: GPL-2.0-only
> >> +/*
> >> + * Virtual Power Management Controller Driver
> >> + *
> >> + * Author: Grzegorz Jaszczyk <jaz@xxxxxxxxxxxx>
> >> + */
> >> +
> >> +#include <linux/acpi.h>
> >> +#include <linux/platform_device.h>
> >> +
> >> +#define ACPI_VIRT_PMC_DSM_UUID "9ea49ba3-434a-49a6-be30-37cc55c4d397"
> >> +#define ACPI_VIRT_PMC_NOTIFY 1
> >> +
> >> +static acpi_handle virt_pmc_handle;
> >> +
> >> +static void virt_pmc_s2idle_notify(void)
> >> +{
> >> + union acpi_object *out_obj;
> >> + guid_t dsm_guid;
> >> +
> >> + guid_parse(ACPI_VIRT_PMC_DSM_UUID, &dsm_guid);
> >> +
> >> + out_obj = acpi_evaluate_dsm(virt_pmc_handle, &dsm_guid,
> >> + 0, ACPI_VIRT_PMC_NOTIFY, NULL);
> >> +
> >> + acpi_handle_debug(virt_pmc_handle, "_DSM function %u evaluation %s\n",
> >> + ACPI_VIRT_PMC_NOTIFY, out_obj ? "successful" : "failed");
> >> +
> >> + ACPI_FREE(out_obj);
> >> +}
> >> +
> >> +static struct acpi_s2idle_dev_ops pmc_s2idle_dev_ops = {
> >> + .check = virt_pmc_s2idle_notify,
> >> +};
> >> +
> >> +static int virt_pmc_probe(struct platform_device *pdev)
> >> +{
> >> + int err = 0;
> >> + guid_t dsm_guid;
> >> +
> >> + virt_pmc_handle = ACPI_HANDLE(&pdev->dev);
> >> +
> >> + guid_parse(ACPI_VIRT_PMC_DSM_UUID, &dsm_guid);
> >> +
> >> + if (!acpi_check_dsm(virt_pmc_handle, &dsm_guid, 0,
> >> + 1 << ACPI_VIRT_PMC_NOTIFY)) {
> >> + dev_err(&pdev->dev, "DSM method doesn't support ACPI_VIRT_PMC_NOTIFY\n");
> >> + return -ENODEV;
> >> + }
> >> +
> >> + err = acpi_register_lps0_dev(&pmc_s2idle_dev_ops);
> >> + if (err)
> >> + dev_err(&pdev->dev, "failed to register LPS0 sleep handler\n");
> >> +
> >> + return err;
> >> +}
> >> +
> >> +static int virt_pmc_remove(struct platform_device *pdev)
> >> +{
> >> + acpi_unregister_lps0_dev(&pmc_s2idle_dev_ops);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> +static const struct acpi_device_id virt_pmc_acpi_ids[] = {
> >> + {"HYPE0001", 0}, /* _HID for XXX Power Engine, _CID PNP0D80*/
> >> + { }
> >> +};
> >> +MODULE_DEVICE_TABLE(acpi, virt_pmc_acpi_ids);
> >> +
> >> +static struct platform_driver virt_pmc_driver = {
> >> + .driver = {
> >> + .name = "virtual_pmc",
> >> + .acpi_match_table = ACPI_PTR(virt_pmc_acpi_ids),
> >> + },
> >> + .probe = virt_pmc_probe,
> >> + .remove = virt_pmc_remove,
> >> +};
> >> +
> >> +module_platform_driver(virt_pmc_driver);
> >> +
> >> +MODULE_LICENSE("GPL");
> >> +MODULE_DESCRIPTION("Virtual PMC Driver");
> >> --
> >> 2.39.1.581.gbfd45094c4-goog
> >>
> >
>