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SubjectRe: [PATCH 0/4] x86/mm/cpa: Fix cpa-array TLB invalidation
Date
Hi Peter,

After updating my UMDs (mesa/etc) over the weekend I cannot reproduce
the bug to begin with. I'll try jumping directly to the intersection
and see if I can reproduce the fault there otherwise I'll have to
rollback my umds.

Hopefully I can test this tomorrow.

Tom

On 2018-12-03 10:41 a.m., Peter Zijlstra wrote:
> On Fri, Nov 30, 2018 at 04:19:46PM +0000, StDenis, Tom wrote:
>> NAK I get a failure in TTM on init with your x86/mm branch (see attached
>> dmesg).
>
> So the good news is that with some additional self-tests I can trivially
> reproduce this. The bad news is that an otherwise straight forward
> cleanup seems to make CPA horribly mad at me.
>
> And since we're somewhat late in the release cycle, I suppose we should
> do the simple thing first, and then I can try and figure out this CPA
> mess later.
>
> So how about this relatively simple partial revert to sort the problem.
>
> ---
> Subject: x86/mm/cpa: Fix cpa_flush_array() TLB invalidation
>
> In commit:
>
> a7295fd53c39 ("x86/mm/cpa: Use flush_tlb_kernel_range()")
>
> I misread the cpa array code and incorrectly used
> tlb_flush_kernel_range(), resulting in missing TLB flushes and
> consequent failures.
>
> Instead do a full invalidate in this case -- for now.
>
> Fixes: a7295fd53c39 ("x86/mm/cpa: Use flush_tlb_kernel_range()")
> Reported-by: "StDenis, Tom" <Tom.StDenis@amd.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> arch/x86/mm/pageattr.c | 24 ++++++++++++++++--------
> 1 file changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
> index bac35001d896..61bc7d1800d7 100644
> --- a/arch/x86/mm/pageattr.c
> +++ b/arch/x86/mm/pageattr.c
> @@ -285,20 +285,16 @@ static void cpa_flush_all(unsigned long cache)
> on_each_cpu(__cpa_flush_all, (void *) cache, 1);
> }
>
> -static bool __cpa_flush_range(unsigned long start, int numpages, int cache)
> +static bool __inv_flush_all(int cache)
> {
> BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);
>
> - WARN_ON(PAGE_ALIGN(start) != start);
> -
> if (cache && !static_cpu_has(X86_FEATURE_CLFLUSH)) {
> cpa_flush_all(cache);
> return true;
> }
>
> - flush_tlb_kernel_range(start, start + PAGE_SIZE * numpages);
> -
> - return !cache;
> + return false;
> }
>
> static void cpa_flush_range(unsigned long start, int numpages, int cache)
> @@ -306,7 +302,14 @@ static void cpa_flush_range(unsigned long start, int numpages, int cache)
> unsigned int i, level;
> unsigned long addr;
>
> - if (__cpa_flush_range(start, numpages, cache))
> + WARN_ON(PAGE_ALIGN(start) != start);
> +
> + if (__inv_flush_all(cache))
> + return;
> +
> + flush_tlb_kernel_range(start, start + PAGE_SIZE * numpages);
> +
> + if (!cache)
> return;
>
> /*
> @@ -332,7 +335,12 @@ static void cpa_flush_array(unsigned long baddr, unsigned long *start,
> {
> unsigned int i, level;
>
> - if (__cpa_flush_range(baddr, numpages, cache))
> + if (__inv_flush_all(cache))
> + return;
> +
> + flush_tlb_all();
> +
> + if (!cache)
> return;
>
> /*
>

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