linux-kernel - [PATCH 3.16 083/134] x86/mm: Fix flush_tlb

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Date:   Fri, 18 Aug 2017 14:13:20 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Brian Gerst" <brgerst@...il.com>,
        "Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>,
        "Boris Ostrovsky" <boris.ostrovsky@...cle.com>,
        "Ingo Molnar" <mingo@...nel.org>,
        "Juergen Gross" <jgross@...e.com>, "Nadav Amit" <namit@...are.com>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Andy Lutomirski" <luto@...nel.org>,
        "Dave Hansen" <dave.hansen@...el.com>,
        "Denys Vlasenko" <dvlasenk@...hat.com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "H. Peter Anvin" <hpa@...or.com>, "Michal Hocko" <mhocko@...e.com>,
        "Josh Poimboeuf" <jpoimboe@...hat.com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Rik van Riel" <riel@...hat.com>, "Borislav Petkov" <bp@...en8.de>
Subject: [PATCH 3.16 083/134] x86/mm: Fix flush_tlb_page() on Xen

3.16.47-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <luto@...nel.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@...nel.org>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Nadav Amit <namit@...are.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.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@...nel.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@...adent.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();
 }