Messages in this thread | | | Date | Tue, 31 Jan 2023 12:49:54 -0600 | Subject | Re: [PATCH v1 3/8] x86/psp: Register PSP platform device when ASP table is present | From | Tom Lendacky <> |
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On 1/23/23 09:22, Jeremi Piotrowski wrote: > The ASP table contains the memory location of the register window for > communication with the Platform Security Processor. The device is not > exposed as an acpi node, so it is necessary to probe for the table and > register a platform_device to represent it in the kernel. > > At least conceptually, the same PSP may be exposed on the PCIe bus as > well, in which case it would be necessary to choose whether to use a PCI > BAR or the register window defined in ASPT for communication. There is > no advantage to using the ACPI and there are no known bare-metal systems > that expose the ASP table, so device registration is restricted to the > only systems known to provide an ASPT: Hyper-V VMs. Hyper-V VMs also do > not expose the PSP over PCIe. > > This is a skeleton device at this point, as the ccp driver is not yet > prepared to correctly probe it. Interrupt configuration will come later > on as well. > > Signed-off-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com> > --- > arch/x86/kernel/Makefile | 2 +- > arch/x86/kernel/psp.c | 39 +++++++++++++++++++++++++++++++++++++++
Based on comments about other SEV related items, this should probably be moved into the arch/x86/coco/sev/ directory.
Thanks, Tom
> 2 files changed, 40 insertions(+), 1 deletion(-) > create mode 100644 arch/x86/kernel/psp.c > > diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile > index f901658d9f7c..e2e19f2d08a7 100644 > --- a/arch/x86/kernel/Makefile > +++ b/arch/x86/kernel/Makefile > @@ -139,7 +139,7 @@ obj-$(CONFIG_UNWINDER_ORC) += unwind_orc.o > obj-$(CONFIG_UNWINDER_FRAME_POINTER) += unwind_frame.o > obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o > > -obj-$(CONFIG_AMD_MEM_ENCRYPT) += sev.o > +obj-$(CONFIG_AMD_MEM_ENCRYPT) += psp.o sev.o > > obj-$(CONFIG_CFI_CLANG) += cfi.o > > diff --git a/arch/x86/kernel/psp.c b/arch/x86/kernel/psp.c > new file mode 100644 > index 000000000000..d404df47cc04 > --- /dev/null > +++ b/arch/x86/kernel/psp.c > @@ -0,0 +1,39 @@ > +// SPDX-License-Identifier: GPL-2.0-only > + > +#include <linux/platform_data/psp.h> > +#include <linux/platform_device.h> > +#include <asm/hypervisor.h> > + > +static struct platform_device psp_device = { > + .name = "psp", > + .id = PLATFORM_DEVID_NONE, > +}; > + > +static int __init psp_init_platform_device(void) > +{ > + struct psp_platform_data pdata = {}; > + struct resource res[1]; > + int err; > + > + /* > + * The ACPI PSP interface is mutually exclusive with the PCIe interface, > + * but there is no reason to use the ACPI interface over the PCIe one. > + * Restrict probing ACPI PSP to platforms known to only expose the ACPI > + * interface, which at this time is SNP-host capable Hyper-V VMs. > + */ > + if (!hypervisor_is_type(X86_HYPER_MS_HYPERV)) > + return -ENODEV; > + > + err = acpi_parse_aspt(res, &pdata); > + if (err) > + return err; > + err = platform_device_add_resources(&psp_device, res, 1); > + if (err) > + return err; > + > + err = platform_device_register(&psp_device); > + if (err) > + return err; > + return 0; > +} > +device_initcall(psp_init_platform_device);
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