Messages in this thread | | | Date | Mon, 20 Mar 2023 20:37:56 +0100 | Subject | Re: [PATCH v3 3/8] x86/psp: Register PSP platform device when ASP table is present | From | Jeremi Piotrowski <> |
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On 20/03/2023 20:25, Borislav Petkov wrote: > On Mon, Mar 20, 2023 at 07:19:51PM +0000, 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. >> >> Acked-by: Tom Lendacky <thomas.lendacky@amd.com> >> Signed-off-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com> >> --- >> arch/x86/kernel/Makefile | 1 + >> arch/x86/kernel/psp.c | 42 ++++++++++++++++++++++++++++++++++++++++ > > If this is a platform device (driver), why isn't it part of > the drivers/platform/x86/ lineup? >
Because of patch 4. My thinking was that the irq setup requires poking at intimate architectural details (init_irq_alloc_info etc.) so it seems like it fits in arch/x86.
I also drew inspiration from the sev-guest device in the arch/x86/kernel/sev.c, which is used in a similar context (the PSP device I am registering here is for SNP-host support).
Would you prefer it in drivers/platform/x86?
Jeremi
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