Re: [RESEND RFCv2 1/1] platform/x86: Add virtual PMC driver used for S2Idle

Grzegorz Jaszczyk
2023-02-10T10:56:22Z

czw., 9 lut 2023 o 19:25 Limonciello, Mario
<Mario.Limonciello@amd.com> napisał(a):
>
> [AMD Official Use Only - General]
>
>
>
> > -----Original Message-----
> > From: Grzegorz Jaszczyk <jaz@semihalf.com>
> > Sent: Thursday, February 9, 2023 09:21
> > To: linux-kernel@vger.kernel.org; rafael@kernel.org
> > Cc: dmy@semihalf.com; tn@semihalf.com; dbehr@google.com;
> > zide.chen@intel.corp-partner.google.com; seanjc@google.com;
> > upstream@semihalf.com; hdegoede@redhat.com; markgross@kernel.org;
> > dtor@google.com; Limonciello, Mario <Mario.Limonciello@amd.com>; linux-
> > pm@vger.kernel.org; x86@kernel.org; platform-driver-x86@vger.kernel.org;
> > Grzegorz Jaszczyk <jaz@semihalf.com>
> > Subject: [RESEND RFCv2 1/1] platform/x86: Add virtual PMC driver used for
> > S2Idle
> >
> > 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@semihalf.com>
> > ---
> > Changelog v1..v2:
> > - Take advantage of acpi_s2idle_dev_ops's check() instead of notify()
> > ---
> > drivers/platform/x86/Kconfig | 7 ++++
> > drivers/platform/x86/Makefile | 3 ++
> > drivers/platform/x86/virt_pmc.c | 73
> > +++++++++++++++++++++++++++++++++
> > 3 files changed, 83 insertions(+)
> > create mode 100644 drivers/platform/x86/virt_pmc.c
> >
> > diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> > index 5692385e2d26..b7c3f98031d7 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 "Virt PMC"
> > + depends on ACPI && SUSPEND
> > + 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..daf9c9ed86e5
> > --- /dev/null
> > +++ b/drivers/platform/x86/virt_pmc.c
> > @@ -0,0 +1,73 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Virtual Power Management Controller Driver
> > + *
> > + * Author: Grzegorz Jaszczyk <jaz@semihalf.com>
> > + */
> > +
> > +#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;
> > + static 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 amd_pmc_s2idle_dev_ops = {
> > + .check = virt_pmc_s2idle_notify,
> > +};
> > +
> > +static int virt_pmc_probe(struct platform_device *pdev)
> > +{
> > + int err = 0;
> > +
> > + virt_pmc_handle = ACPI_HANDLE(&pdev->dev);
> > +
> > + err = acpi_register_lps0_dev(&amd_pmc_s2idle_dev_ops);
> > + if (err)
> > + dev_warn(&pdev->dev, "failed to register LPS0 sleep
> > handler\n");
> > +
>
> Besides registering, I would think you also want to have a query to the
> _DSM to determine what functions are available. It could allow this to
> scale better if you're going to need to introduce a new function again
> later for a different reason.
>

Ok, I will add such a query. Thanks