* Vasant Hegde <hegdevas...@linux.vnet.ibm.com> [2019-10-02 13:18:56]:
> Add check to validate whether requested page is part of system RAM
> or not before mmap() and error out if its not part of system RAM.
>
> cat /proc/iomem:
> -----------------
> 00000000-27ffffffff : System RAM
> 2800000000-2fffffffff : namespace0.0
> 200000000000-2027ffffffff : System RAM
> 202800000000-202fffffffff : namespace1.0
> 6000000000000-6003fbfffffff : pciex@600c3c0000000
> 6004000000000-6007f7fffffff : pciex@600c3c0100000
> ....
> ....
>
> Sample dmesg output with this fix:
> ----------------------------------
> [ 160.371911] opal-prd: mmap: Requested page is not part of system RAM (addr
> : 0x0000202ffcfc0000, size : 0x0000000000570000)
> [ 160.665366] opal-prd: mmap: Requested page is not part of system RAM (addr
> : 0x0000202ffcfc0000, size : 0x0000000000570000)
> [ 160.914627] opal-prd: mmap: Requested page is not part of system RAM (addr
> : 0x0000202ffcfc0000, size : 0x0000000000570000)
> [ 161.165253] opal-prd: mmap: Requested page is not part of system RAM (addr
> : 0x0000202ffcfc0000, size : 0x0000000000570000)
> [ 161.414604] opal-prd: mmap: Requested page is not part of system RAM (addr
> : 0x0000202ffcfc0000, size : 0x0000000000570000)
Thanks Vasant for the patch. HBRT pages landing in NVDIMM area caused
the opal-prd failure. Good debug and root-cause.
Thanks to Aneesh for the tip to look into ATT bits of the PTE mapping.
> CC: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
> CC: Jeremy Kerr <j...@ozlabs.org>
> CC: Vaidyanathan Srinivasan <sva...@linux.vnet.ibm.com>
> Signed-off-by: Vasant Hegde <hegdevas...@linux.vnet.ibm.com>
Signed-off-by: Vaidyanathan Srinivasan <sva...@linux.ibm.com>
> ---
> arch/powerpc/platforms/powernv/opal-prd.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/powernv/opal-prd.c
> b/arch/powerpc/platforms/powernv/opal-prd.c
> index 45f4223a790f..0f88752302a2 100644
> --- a/arch/powerpc/platforms/powernv/opal-prd.c
> +++ b/arch/powerpc/platforms/powernv/opal-prd.c
> @@ -3,7 +3,7 @@
> * OPAL Runtime Diagnostics interface driver
> * Supported on POWERNV platform
> *
> - * Copyright IBM Corporation 2015
> + * Copyright IBM Corporation 2015-2019
> */
>
> #define pr_fmt(fmt) "opal-prd: " fmt
> @@ -47,6 +47,20 @@ static bool opal_prd_range_is_valid(uint64_t addr,
> uint64_t size)
> if (addr + size < addr)
> return false;
>
> + /*
> + * Check if region is in system RAM and error out if the address
> + * belongs to special devices like NVDIMM. phys_mem_access_prot()
> + * routine will change ATT bits to non cachable if page is not in
> + * RAM, causing HBRT to not fetch and execute in the mapped memory
> + * and fail. Page permissions can be left at default since all
> + * firmware component should be in system RAM only.
> + */
> + if (!page_is_ram(addr >> PAGE_SHIFT)) {
> + pr_warn("mmap: Requested page is not part of system RAM "
> + "(addr : 0x%016llx, size : 0x%016llx)\n", addr, size);
> + return false;
> + }
> +
> parent = of_find_node_by_path("/reserved-memory");
> if (!parent)
> return false;
> --
> 2.21.0
>
