[PATCH] x86/uv: fix incorrect tlb flush issue

From: Alex Shi
Date: Thu Sep 06 2012 - 22:38:36 EST

The flush tlb optimization code has logical issue on UV platform.
It doesn't flush the full range at all, since it simply
ignores its 'end' parameter (and hence also the "all" indicator)
in uv_flush_tlb_others() function.

I have tried to embed the start/end on UV code, but finally find the
'payload' message format embedded hardware filled vector. So be lacking
the enough knowledge of the hardware, I just check the start/end fair
in uv_flush_tlb_others(): except single page flush, will flush
all TLB entries for other situations.

Reported-by: Jan Beulich <jbeulich@xxxxxxxx>
Signed-off-by: Alex Shi <alex.shi@xxxxxxxxx>
Cc: Jack Steiner <steiner@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
arch/x86/platform/uv/tlb_uv.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
index b8b3a37..582836e 100644
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -1034,7 +1034,8 @@ static int set_distrib_bits(struct cpumask *flush_mask, struct bau_control *bcp,
* globally purge translation cache of a virtual address or all TLB's
* @cpumask: mask of all cpu's in which the address is to be removed
* @mm: mm_struct containing virtual address range
- * @va: virtual address to be removed (or TLB_FLUSH_ALL for all TLB's on cpu)
+ * @start: start virtual address to be removed from TLB
+ * @end: end virtual address to be remove from TLB
* @cpu: the current cpu
* This is the entry point for initiating any UV global TLB shootdown.
@@ -1113,7 +1114,10 @@ const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask,

record_send_statistics(stat, locals, hubs, remotes, bau_desc);

- bau_desc->payload.address = start;
+ if (!end || (end - start) <= PAGE_SIZE)
+ bau_desc->payload.address = start;
+ else
+ bau_desc->payload.address = TLB_FLUSH_ALL;
bau_desc->payload.sending_cpu = cpu;
* uv_flush_send_and_wait returns 0 if all cpu's were messaged,

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