Re: [PATCH] selftests/mm: Update va_high_addr_switch.sh to check CPU for la57 flag

[Andrew Morton]

On Wed, 24 Jan 2024 08:39:33 -0500 Audra Mitchell <audra@xxxxxxxxxx> wrote:

> > A more complete description of these "test failures" would be helpful
> > please.
> > 
> 
> Hey, sorry for the incomplete description. The test does a series of mmap
> calls including three using the MAP_FIXED flag and specifying an address that
> is 1<<47 or 1<<48. These addresses are only available if you are using level 5
> page tables, which requires both the CPU to have the capabiltiy (la57 flag)
> and the kernel to be configured. Currently the test only checks for the kernel
> configuration option, so this test can still report a false positive. Here are
> the three failing lines:
> 
> $ ./va_high_addr_switch | grep FAILED
> mmap(ADDR_SWITCH_HINT, 2 * PAGE_SIZE, MAP_FIXED): 0xffffffffffffffff - FAILED
> mmap(HIGH_ADDR, MAP_FIXED): 0xffffffffffffffff - FAILED
> mmap(ADDR_SWITCH_HINT, 2 * PAGE_SIZE, MAP_FIXED): 0xffffffffffffffff - FAILED
> 
> I thought (for about a second) refactoring the test so that these three mmap
> calls will only be run on systems with the level 5 page tables available, but
> the whole point of the test is to check the level 5 feature...
> 
> If you would like me to also update the description on the patch let me know
> and I'll update it and resubmit. Thanks!

I pasted the above into the changelog, thanks.