On Thu, Feb 03, 2022 at 07:31:24PM +0000, Robin Murphy wrote:
> The original version of the IORT PMCG definition had an oversight
> wherein there was no way to describe the second register page for an
> implementation using the recommended RELOC_CTRS feature. Although the
> spec was fixed, and the final patches merged to ACPICA and Linux written
> against the new version, it seems that some old firmware based on the
> original revision has survived and turned up in the wild.
>
> Add a check for the original PMCG definition, and avoid filling in the
> second memory resource with nonsense if so. Otherwise it is likely that
> something horrible will happen when the PMCG driver attempts to probe.
>
> Reported-by: Michael Petlan <mpetlan@xxxxxxxxxx>
> Fixes: 24e516049360 ("ACPI/IORT: Add support for PMCG")
> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
> ---
>
> v2: Simpler workaround, since I realised platform_get_resource()
> should happily just skip over a zero-initialised hole in the
> resource array.
>
> drivers/acpi/arm64/iort.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Should we send it to stable kernels ?
I'd kindly ask Catalin/Will to pick it up please.
Thanks,
Lorenzo
>
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 175397913be1..7092b94b2aae 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -1371,9 +1371,17 @@ static void __init arm_smmu_v3_pmcg_init_resources(struct resource *res,
> res[0].start = pmcg->page0_base_address;
> res[0].end = pmcg->page0_base_address + SZ_4K - 1;
> res[0].flags = IORESOURCE_MEM;
> - res[1].start = pmcg->page1_base_address;
> - res[1].end = pmcg->page1_base_address + SZ_4K - 1;
> - res[1].flags = IORESOURCE_MEM;
> + /*
> + * The initial version in DEN0049C lacked a way to describe register
> + * page 1, which makes it broken for most PMCG implementations; in
> + * that case, just let the driver fail gracefully if it expects to
> + * find a second memory resource.
> + */
> + if (node->revision > 0) {
> + res[1].start = pmcg->page1_base_address;
> + res[1].end = pmcg->page1_base_address + SZ_4K - 1;
> + res[1].flags = IORESOURCE_MEM;
> + }
>
> if (pmcg->overflow_gsiv)
> acpi_iort_register_irq(pmcg->overflow_gsiv, "overflow",
> --
> 2.28.0.dirty
>
