190 lines
5.9 KiB
Diff
190 lines
5.9 KiB
Diff
# HG changeset patch
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# Parent 5a299906312e606553e6dd2acbe44ab692722a75
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xenpaging: improve evict error handling
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Adjust return codes in Xen and handle errors in evict_victim() properly.
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p2m_mem_paging_nominate() returns -EAGAIN, p2m_mem_paging_evict()
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returns -EBUSY. Other errors indicate guest failures, which
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xenpaging_evict_page() can now catch correctly. Also write() failures
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are fatal.
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Without this change, evict_victim() may spin forever if the guest is
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killed because this function does not get a signal.
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Signed-off-by: Olaf Hering <olaf@aepfle.de>
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---
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tools/xenpaging/xenpaging.c | 47 ++++++++++++++++++++++++++---------------
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xen/arch/x86/mm/p2m.c | 7 +-----
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xen/include/public/mem_event.h | 2 -
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3 files changed, 33 insertions(+), 23 deletions(-)
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Index: xen-4.1.2-testing/tools/xenpaging/xenpaging.c
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===================================================================
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--- xen-4.1.2-testing.orig/tools/xenpaging/xenpaging.c
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+++ xen-4.1.2-testing/tools/xenpaging/xenpaging.c
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@@ -569,29 +569,35 @@ static int xenpaging_evict_page(xenpagin
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xc_interface *xch = paging->xc_handle;
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void *page;
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unsigned long gfn;
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- int ret;
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+ int ret = -1;
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DECLARE_DOMCTL;
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/* Map page to get a handle */
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gfn = victim->gfn;
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- ret = -EFAULT;
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page = xc_map_foreign_pages(xch, paging->mem_event.domain_id,
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PROT_READ | PROT_WRITE, &gfn, 1);
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if ( page == NULL )
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{
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- PERROR("Error mapping page %lx", victim->gfn);
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+ if ( errno == EINVAL )
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+ ret = 1;
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+ else
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+ PERROR("Error mapping page %lx", victim->gfn);
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goto out;
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}
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/* Nominate the page */
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- ret = xc_mem_paging_nominate(xch, paging->mem_event.domain_id, gfn);
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- if ( ret != 0 )
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+ if ( xc_mem_paging_nominate(xch, paging->mem_event.domain_id, gfn) )
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+ {
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+ if ( errno == EAGAIN )
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+ ret = 1;
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+ else
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+ PERROR("Error nominating page %lx", victim->gfn);
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goto out;
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+ }
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/* Copy page */
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- ret = write_page(fd, page, i);
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- if ( ret != 0 )
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+ if ( write_page(fd, page, i) )
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{
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PERROR("Error copying page %lx", victim->gfn);
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goto out;
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@@ -601,10 +607,10 @@ static int xenpaging_evict_page(xenpagin
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page = NULL;
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/* Tell Xen to evict page */
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- ret = xc_mem_paging_evict(xch, paging->mem_event.domain_id,
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- victim->gfn);
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- if ( ret != 0 )
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+ if ( xc_mem_paging_evict(xch, paging->mem_event.domain_id, victim->gfn) )
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{
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+ if ( errno == EBUSY )
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+ ret = 1;
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PERROR("Error evicting page %lx", victim->gfn);
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goto out;
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}
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@@ -616,6 +622,8 @@ static int xenpaging_evict_page(xenpagin
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/* Record number of evicted pages */
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paging->num_paged_out++;
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+ ret = 0;
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+
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out:
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if (page)
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munmap(page, PAGE_SIZE);
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@@ -724,7 +732,7 @@ static int evict_victim(xenpaging_t *pag
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xenpaging_victim_t *victim, int fd, int i)
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{
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xc_interface *xch = paging->xc_handle;
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- int j = 0;
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+ static int num_paged_out;
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int ret;
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do
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@@ -732,9 +740,13 @@ static int evict_victim(xenpaging_t *pag
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ret = policy_choose_victim(paging, victim);
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if ( ret != 0 )
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{
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- if ( ret != -ENOSPC )
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- ERROR("Error choosing victim");
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- goto out;
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+ if ( num_paged_out != paging->num_paged_out ) {
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+ DPRINTF("Flushing qemu cache\n");
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+ xenpaging_mem_paging_flush_ioemu_cache(paging);
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+ num_paged_out = paging->num_paged_out;
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+ }
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+ ret = -ENOSPC;
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+ goto out;
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}
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if ( interrupted )
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@@ -742,11 +754,12 @@ static int evict_victim(xenpaging_t *pag
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ret = -EINTR;
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goto out;
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}
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+
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ret = xenpaging_evict_page(paging, victim, fd, i);
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- if ( ret && j++ % 1000 == 0 )
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+ if ( ret < 0 )
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{
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- if ( xenpaging_mem_paging_flush_ioemu_cache(paging) )
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- PERROR("Error flushing ioemu cache");
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+ ret = -EINTR;
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+ goto out;
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}
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}
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while ( ret );
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Index: xen-4.1.2-testing/xen/arch/x86/mm/p2m.c
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===================================================================
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--- xen-4.1.2-testing.orig/xen/arch/x86/mm/p2m.c
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+++ xen-4.1.2-testing/xen/arch/x86/mm/p2m.c
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@@ -2863,19 +2863,17 @@ int p2m_mem_paging_nominate(struct p2m_d
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p2m_type_t p2mt;
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p2m_access_t a;
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mfn_t mfn;
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- int ret;
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+ int ret = -EAGAIN;
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p2m_lock(p2m);
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mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, p2m_query);
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/* Check if mfn is valid */
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- ret = -EINVAL;
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if ( !mfn_valid(mfn) )
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goto out;
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/* Check p2m type */
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- ret = -EAGAIN;
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if ( !p2m_is_pageable(p2mt) )
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goto out;
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@@ -2928,7 +2926,7 @@ int p2m_mem_paging_evict(struct p2m_doma
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p2m_access_t a;
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mfn_t mfn;
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struct domain *d = p2m->domain;
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- int ret = -EINVAL;
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+ int ret = -EBUSY;
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p2m_lock(p2m);
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@@ -2941,7 +2939,6 @@ int p2m_mem_paging_evict(struct p2m_doma
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if ( p2mt != p2m_ram_paging_out )
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goto out;
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- ret = -EBUSY;
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/* Get the page so it doesn't get modified under Xen's feet */
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page = mfn_to_page(mfn);
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if ( unlikely(!get_page(page, d)) )
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Index: xen-4.1.2-testing/xen/include/public/mem_event.h
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===================================================================
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--- xen-4.1.2-testing.orig/xen/include/public/mem_event.h
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+++ xen-4.1.2-testing/xen/include/public/mem_event.h
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@@ -49,7 +49,7 @@
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#define MEM_EVENT_REASON_INT3 5 /* int3 was hit: gla/gfn are RIP */
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#define MEM_EVENT_REASON_SINGLESTEP 6 /* single step was invoked: gla/gfn are RIP */
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-#define MEM_EVENT_PAGING_AGE 2UL /* Number distinguish the mem_paging <-> pager interface */
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+#define MEM_EVENT_PAGING_AGE 3UL /* Number distinguish the mem_paging <-> pager interface */
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typedef struct mem_event_shared_page {
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uint32_t port;
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