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169 lines
4.8 KiB
169 lines
4.8 KiB
Subject: Add fallback when XENMEM_exchange fails to replace contiguous region
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From: jbeulich@novell.com
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Patch-mainline: obsolete
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References: 181869
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This avoids losing precious special memory in places where any memory can be
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used.
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--- head-2010-12-08.orig/arch/x86/mm/hypervisor.c 2010-12-08 10:38:40.000000000 +0100
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+++ head-2010-12-08/arch/x86/mm/hypervisor.c 2010-12-08 10:45:24.000000000 +0100
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@@ -43,6 +43,7 @@
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#include <xen/interface/memory.h>
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#include <linux/module.h>
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#include <linux/percpu.h>
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+#include <linux/highmem.h>
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#include <asm/tlbflush.h>
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#include <linux/highmem.h>
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@@ -717,6 +718,83 @@ void xen_destroy_contiguous_region(unsig
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BUG();
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balloon_unlock(flags);
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+
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+ if (unlikely(!success)) {
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+ /* Try hard to get the special memory back to Xen. */
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+ exchange.in.extent_order = 0;
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+ set_xen_guest_handle(exchange.in.extent_start, &in_frame);
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+
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+ for (i = 0; i < (1U<<order); i++) {
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+ struct page *page = alloc_page(__GFP_HIGHMEM|__GFP_COLD);
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+ unsigned long pfn;
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+ mmu_update_t mmu;
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+ unsigned int j = 0;
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+
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+ if (!page) {
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+ pr_warning("Xen and kernel out of memory"
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+ " while trying to release an order"
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+ " %u contiguous region\n", order);
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+ break;
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+ }
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+ pfn = page_to_pfn(page);
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+
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+ balloon_lock(flags);
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+
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+ if (!PageHighMem(page)) {
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+ void *v = __va(pfn << PAGE_SHIFT);
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+
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+ scrub_pages(v, 1);
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+ MULTI_update_va_mapping(cr_mcl + j, (unsigned long)v,
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+ __pte_ma(0), UVMF_INVLPG|UVMF_ALL);
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+ ++j;
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+ }
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+#ifdef CONFIG_XEN_SCRUB_PAGES
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+ else {
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+ scrub_pages(kmap(page), 1);
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+ kunmap(page);
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+ kmap_flush_unused();
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+ }
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+#endif
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+
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+ frame = pfn_to_mfn(pfn);
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+ set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
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+
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+ MULTI_update_va_mapping(cr_mcl + j, vstart,
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+ pfn_pte_ma(frame, PAGE_KERNEL),
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+ UVMF_INVLPG|UVMF_ALL);
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+ ++j;
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+
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+ pfn = __pa(vstart) >> PAGE_SHIFT;
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+ set_phys_to_machine(pfn, frame);
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+ if (!xen_feature(XENFEAT_auto_translated_physmap)) {
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+ mmu.ptr = ((uint64_t)frame << PAGE_SHIFT) | MMU_MACHPHYS_UPDATE;
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+ mmu.val = pfn;
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+ cr_mcl[j].op = __HYPERVISOR_mmu_update;
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+ cr_mcl[j].args[0] = (unsigned long)&mmu;
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+ cr_mcl[j].args[1] = 1;
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+ cr_mcl[j].args[2] = 0;
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+ cr_mcl[j].args[3] = DOMID_SELF;
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+ ++j;
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+ }
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+
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+ cr_mcl[j].op = __HYPERVISOR_memory_op;
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+ cr_mcl[j].args[0] = XENMEM_decrease_reservation;
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+ cr_mcl[j].args[1] = (unsigned long)&exchange.in;
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+
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+ if (HYPERVISOR_multicall(cr_mcl, j + 1))
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+ BUG();
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+ BUG_ON(cr_mcl[j].result != 1);
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+ while (j--)
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+ BUG_ON(cr_mcl[j].result != 0);
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+
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+ balloon_unlock(flags);
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+
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+ free_empty_pages(&page, 1);
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+
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+ in_frame++;
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+ vstart += PAGE_SIZE;
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+ }
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+ }
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}
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EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
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--- head-2010-12-08.orig/drivers/xen/balloon/balloon.c 2010-11-25 13:47:53.000000000 +0100
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+++ head-2010-12-08/drivers/xen/balloon/balloon.c 2010-11-25 13:48:02.000000000 +0100
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@@ -773,7 +773,11 @@ struct page **alloc_empty_pages_and_page
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}
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EXPORT_SYMBOL_GPL(alloc_empty_pages_and_pagevec);
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-void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages)
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+#endif /* CONFIG_XEN_BACKEND */
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+
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+#ifdef CONFIG_XEN
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+static void _free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages,
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+ bool free_vec)
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{
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unsigned long flags;
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int i;
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@@ -784,17 +788,33 @@ void free_empty_pages_and_pagevec(struct
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balloon_lock(flags);
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for (i = 0; i < nr_pages; i++) {
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BUG_ON(page_count(pagevec[i]) != 1);
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- balloon_append(pagevec[i], 0);
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+ balloon_append(pagevec[i], !free_vec);
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+ }
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+ if (!free_vec) {
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+ bs.current_pages -= nr_pages;
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+ totalram_pages = bs.current_pages - totalram_bias;
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}
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balloon_unlock(flags);
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- kfree(pagevec);
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+ if (free_vec)
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+ kfree(pagevec);
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schedule_work(&balloon_worker);
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}
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-EXPORT_SYMBOL_GPL(free_empty_pages_and_pagevec);
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-#endif /* CONFIG_XEN_BACKEND */
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+void free_empty_pages(struct page **pagevec, int nr_pages)
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+{
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+ _free_empty_pages_and_pagevec(pagevec, nr_pages, false);
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+}
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+#endif
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+
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+#if defined(CONFIG_XEN_BACKEND) || defined(CONFIG_XEN_BACKEND_MODULE)
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+void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages)
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+{
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+ _free_empty_pages_and_pagevec(pagevec, nr_pages, true);
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+}
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+EXPORT_SYMBOL_GPL(free_empty_pages_and_pagevec);
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+#endif
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void balloon_release_driver_page(struct page *page)
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{
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--- head-2010-12-08.orig/include/xen/balloon.h 2010-11-22 12:57:58.000000000 +0100
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+++ head-2010-12-08/include/xen/balloon.h 2009-06-09 15:52:17.000000000 +0200
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@@ -47,6 +47,10 @@ void balloon_update_driver_allowance(lon
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struct page **alloc_empty_pages_and_pagevec(int nr_pages);
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void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages);
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+/* Free an empty page range (not allocated through
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+ alloc_empty_pages_and_pagevec), adding to the balloon. */
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+void free_empty_pages(struct page **pagevec, int nr_pages);
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+
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void balloon_release_driver_page(struct page *page);
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/*
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