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x86/setup: Move trim_snb_memory() later in setup_arch() to fix boot hangs 

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  a799c2bd29 ("x86/setup: Consolidate early memory reservations")

moved reservation of the memory inaccessible by Sandy Bride integrated
graphics very early, and, as a result, on systems with such devices
the first 1M was reserved by trim_snb_memory() which prevented the
allocation of the real mode trampoline and made the boot hang very
early.

Since the purpose of trim_snb_memory() is to prevent problematic pages
ever reaching the graphics device, it is safe to reserve these pages
after memblock allocations are possible.

Move trim_snb_memory() later in boot so that it will be called after
reserve_real_mode() and make comments describing trim_snb_memory()
operation more elaborate.

 [ bp: Massage a bit. ]

Fixes: a799c2bd29 ("x86/setup: Consolidate early memory reservations")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Hugh Dickins <hughd@google.com>
Link: https://lkml.kernel.org/r/f67d3e03-af90-f790-baf4-8d412fe055af@infradead.org
This commit is contained in:
Mike Rapoport 2021-04-13 21:08:39 +03:00 committed by Borislav Petkov
parent 4c674481dc
commit c361e5d4d0
1 changed files with 15 additions and 5 deletions
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20
arch/x86/kernel/setup.c
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@ -633,11 +633,16 @@ static void __init trim_snb_memory(void)
printk(KERN_DEBUG "reserving inaccessible SNB gfx pages\n");
/*
* Reserve all memory below the 1 MB mark that has not
* already been reserved.
* SandyBridge integrated graphics devices have a bug that prevents
* them from accessing certain memory ranges, namely anything below
* 1M and in the pages listed in bad_pages[] above.
*
* To avoid these pages being ever accessed by SNB gfx devices
* reserve all memory below the 1 MB mark and bad_pages that have
* not already been reserved at boot time.
*/
memblock_reserve(0, 1<<20);
for (i = 0; i < ARRAY_SIZE(bad_pages); i++) {
if (memblock_reserve(bad_pages[i], PAGE_SIZE))
printk(KERN_WARNING "failed to reserve 0x%08lx\n",
@ -746,8 +751,6 @@ static void __init early_reserve_memory(void)
reserve_ibft_region();
reserve_bios_regions();
trim_snb_memory();
}
/*
@ -1081,6 +1084,13 @@ void __init setup_arch(char **cmdline_p)
reserve_real_mode();
/*
* Reserving memory causing GPU hangs on Sandy Bridge integrated
* graphics devices should be done after we allocated memory under
* 1M for the real mode trampoline.
*/
trim_snb_memory();
init_mem_mapping();
idt_setup_early_pf();