[PATCH 3.16 083/134] x86/mm: Fix flush_tlb_page() on Xen

Ben Hutchings
2017-08-18T13:15:50Z

From: Andy Lutomirski <luto@kernel.org>

commit dbd68d8e84c606673ebbcf15862f8c155fa92326 upstream.

flush_tlb_page() passes a bogus range to flush_tlb_others() and
expects the latter to fix it up. native_flush_tlb_others() has the
fixup but Xen's version doesn't. Move the fixup to
flush_tlb_others().

AFAICS the only real effect is that, without this fix, Xen would
flush everything instead of just the one page on remote vCPUs in
when flush_tlb_page() was called.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: e7b52ffd45a6 ("x86/flush_tlb: try flush_tlb_single one by one in flush_tlb_range")
Link: http://lkml.kernel.org/r/10ed0e4dfea64daef10b87fb85df1746999b4dba.1492844372.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.16: the special case was handled in flush_tlb_func(), not
native_flush_tlb_others()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/x86/mm/tlb.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -107,8 +107,6 @@ static void flush_tlb_func(void *info)
if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK) {
if (f->flush_end == TLB_FLUSH_ALL)
local_flush_tlb();
- else if (!f->flush_end)
- __flush_tlb_single(f->flush_start);
else {
unsigned long addr;
addr = f->flush_start;
@@ -248,7 +246,7 @@ void flush_tlb_page(struct vm_area_struc
}

if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
- flush_tlb_others(mm_cpumask(mm), mm, start, 0UL);
+ flush_tlb_others(mm_cpumask(mm), mm, start, start + PAGE_SIZE);

preempt_enable();
}