From: Jeremy Fitzhardinge Date: Wed, 11 Feb 2009 17:32:19 +0000 (-0800) Subject: x86/cpa: make sure cpa is safe to call in lazy mmu mode X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=4f06b0436b2ddbd3b67b10e77098a6862787b3eb;p=linux-2.6-omap-h63xx.git x86/cpa: make sure cpa is safe to call in lazy mmu mode Impact: fix race leading to crash under KVM and Xen The CPA code may be called while we're in lazy mmu update mode - for example, when using DEBUG_PAGE_ALLOC and doing a slab allocation in an interrupt handler which interrupted a lazy mmu update. In this case, the in-memory pagetable state may be out of date due to pending queued updates. We need to flush any pending updates before inspecting the page table. Similarly, we must explicitly flush any modifications CPA may have made (which comes down to flushing queued operations when flushing the TLB). Signed-off-by: Jeremy Fitzhardinge Acked-by: Marcelo Tosatti Cc: Stable Kernel Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 84ba74820ad..f664bc1c409 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -576,6 +576,13 @@ static int __change_page_attr(struct cpa_data *cpa, int primary) else address = *cpa->vaddr; + /* + * If we're called with lazy mmu updates enabled, the + * in-memory pte state may be stale. Flush pending updates to + * bring them up to date. + */ + arch_flush_lazy_mmu_mode(); + repeat: kpte = lookup_address(address, &level); if (!kpte) @@ -854,6 +861,13 @@ static int change_page_attr_set_clr(unsigned long *addr, int numpages, } else cpa_flush_all(cache); + /* + * If we've been called with lazy mmu updates enabled, then + * make sure that everything gets flushed out before we + * return. + */ + arch_flush_lazy_mmu_mode(); + out: return ret; }