From: Anthony PERARD <anthony.perard@citrix.com> To: <qemu-devel@nongnu.org> Cc: Anthony PERARD <anthony.perard@citrix.com>, xen-devel@lists.xenproject.org, Paul Durrant <paul.durrant@citrix.com>, Stefano Stabellini <sstabellini@kernel.org> Subject: [Qemu-devel] [PATCH v2 4/4] xen: Avoid VLA Date: Tue, 18 Jun 2019 12:23:41 +0100 [thread overview] Message-ID: <20190618112341.513-5-anthony.perard@citrix.com> (raw) In-Reply-To: <20190618112341.513-1-anthony.perard@citrix.com> Avoid using a variable length array. We allocate the `dirty_bitmap' buffer only once when we start tracking for dirty bits. Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> --- Notes: v2: - Allocate the bitmap buffer only once when we start tracking dirty bits. (instead of at every function call) Was suggested by Peter here: <CAFEAcA88+A2oCkQnxKDEdpmfCZSmPzWMBg01wDDV68bMZoY5Jg@mail.gmail.com> "should we try to stop using variable length arrays?" hw/i386/xen/xen-hvm.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c index ae3deb4ef3..469f1260a4 100644 --- a/hw/i386/xen/xen-hvm.c +++ b/hw/i386/xen/xen-hvm.c @@ -119,6 +119,8 @@ typedef struct XenIOState { DeviceListener device_listener; hwaddr free_phys_offset; const XenPhysmap *log_for_dirtybit; + /* Buffer used by xen_sync_dirty_bitmap */ + unsigned long *dirty_bitmap; Notifier exit; Notifier suspend; @@ -464,6 +466,8 @@ static int xen_remove_from_physmap(XenIOState *state, QLIST_REMOVE(physmap, list); if (state->log_for_dirtybit == physmap) { state->log_for_dirtybit = NULL; + g_free(state->dirty_bitmap); + state->dirty_bitmap = NULL; } g_free(physmap); @@ -614,7 +618,7 @@ static void xen_sync_dirty_bitmap(XenIOState *state, { hwaddr npages = size >> TARGET_PAGE_BITS; const int width = sizeof(unsigned long) * 8; - unsigned long bitmap[DIV_ROUND_UP(npages, width)]; + size_t bitmap_size = DIV_ROUND_UP(npages, width); int rc, i, j; const XenPhysmap *physmap = NULL; @@ -626,13 +630,14 @@ static void xen_sync_dirty_bitmap(XenIOState *state, if (state->log_for_dirtybit == NULL) { state->log_for_dirtybit = physmap; + state->dirty_bitmap = g_new(unsigned long, bitmap_size); } else if (state->log_for_dirtybit != physmap) { /* Only one range for dirty bitmap can be tracked. */ return; } rc = xen_track_dirty_vram(xen_domid, start_addr >> TARGET_PAGE_BITS, - npages, bitmap); + npages, state->dirty_bitmap); if (rc < 0) { #ifndef ENODATA #define ENODATA ENOENT @@ -646,8 +651,8 @@ static void xen_sync_dirty_bitmap(XenIOState *state, return; } - for (i = 0; i < ARRAY_SIZE(bitmap); i++) { - unsigned long map = bitmap[i]; + for (i = 0; i < bitmap_size; i++) { + unsigned long map = state->dirty_bitmap[i]; while (map != 0) { j = ctzl(map); map &= ~(1ul << j); @@ -677,6 +682,8 @@ static void xen_log_stop(MemoryListener *listener, MemoryRegionSection *section, if (old & ~new & (1 << DIRTY_MEMORY_VGA)) { state->log_for_dirtybit = NULL; + g_free(state->dirty_bitmap); + state->dirty_bitmap = NULL; /* Disable dirty bit tracking */ xen_track_dirty_vram(xen_domid, 0, 0, NULL); } -- Anthony PERARD
WARNING: multiple messages have this Message-ID (diff)
From: Anthony PERARD <anthony.perard@citrix.com> To: <qemu-devel@nongnu.org> Cc: Anthony PERARD <anthony.perard@citrix.com>, xen-devel@lists.xenproject.org, Paul Durrant <paul.durrant@citrix.com>, Stefano Stabellini <sstabellini@kernel.org> Subject: [Xen-devel] [PATCH v2 4/4] xen: Avoid VLA Date: Tue, 18 Jun 2019 12:23:41 +0100 [thread overview] Message-ID: <20190618112341.513-5-anthony.perard@citrix.com> (raw) In-Reply-To: <20190618112341.513-1-anthony.perard@citrix.com> Avoid using a variable length array. We allocate the `dirty_bitmap' buffer only once when we start tracking for dirty bits. Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> --- Notes: v2: - Allocate the bitmap buffer only once when we start tracking dirty bits. (instead of at every function call) Was suggested by Peter here: <CAFEAcA88+A2oCkQnxKDEdpmfCZSmPzWMBg01wDDV68bMZoY5Jg@mail.gmail.com> "should we try to stop using variable length arrays?" hw/i386/xen/xen-hvm.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/hw/i386/xen/xen-hvm.c b/hw/i386/xen/xen-hvm.c index ae3deb4ef3..469f1260a4 100644 --- a/hw/i386/xen/xen-hvm.c +++ b/hw/i386/xen/xen-hvm.c @@ -119,6 +119,8 @@ typedef struct XenIOState { DeviceListener device_listener; hwaddr free_phys_offset; const XenPhysmap *log_for_dirtybit; + /* Buffer used by xen_sync_dirty_bitmap */ + unsigned long *dirty_bitmap; Notifier exit; Notifier suspend; @@ -464,6 +466,8 @@ static int xen_remove_from_physmap(XenIOState *state, QLIST_REMOVE(physmap, list); if (state->log_for_dirtybit == physmap) { state->log_for_dirtybit = NULL; + g_free(state->dirty_bitmap); + state->dirty_bitmap = NULL; } g_free(physmap); @@ -614,7 +618,7 @@ static void xen_sync_dirty_bitmap(XenIOState *state, { hwaddr npages = size >> TARGET_PAGE_BITS; const int width = sizeof(unsigned long) * 8; - unsigned long bitmap[DIV_ROUND_UP(npages, width)]; + size_t bitmap_size = DIV_ROUND_UP(npages, width); int rc, i, j; const XenPhysmap *physmap = NULL; @@ -626,13 +630,14 @@ static void xen_sync_dirty_bitmap(XenIOState *state, if (state->log_for_dirtybit == NULL) { state->log_for_dirtybit = physmap; + state->dirty_bitmap = g_new(unsigned long, bitmap_size); } else if (state->log_for_dirtybit != physmap) { /* Only one range for dirty bitmap can be tracked. */ return; } rc = xen_track_dirty_vram(xen_domid, start_addr >> TARGET_PAGE_BITS, - npages, bitmap); + npages, state->dirty_bitmap); if (rc < 0) { #ifndef ENODATA #define ENODATA ENOENT @@ -646,8 +651,8 @@ static void xen_sync_dirty_bitmap(XenIOState *state, return; } - for (i = 0; i < ARRAY_SIZE(bitmap); i++) { - unsigned long map = bitmap[i]; + for (i = 0; i < bitmap_size; i++) { + unsigned long map = state->dirty_bitmap[i]; while (map != 0) { j = ctzl(map); map &= ~(1ul << j); @@ -677,6 +682,8 @@ static void xen_log_stop(MemoryListener *listener, MemoryRegionSection *section, if (old & ~new & (1 << DIRTY_MEMORY_VGA)) { state->log_for_dirtybit = NULL; + g_free(state->dirty_bitmap); + state->dirty_bitmap = NULL; /* Disable dirty bit tracking */ xen_track_dirty_vram(xen_domid, 0, 0, NULL); } -- Anthony PERARD _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2019-06-18 11:26 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-06-18 11:23 [Qemu-devel] [PATCH v2 0/4] Fix build of Xen support + cleanup Anthony PERARD 2019-06-18 11:23 ` [Xen-devel] " Anthony PERARD 2019-06-18 11:23 ` [Qemu-devel] [PATCH v2 1/4] xen: Fix build with public headers Anthony PERARD 2019-06-18 11:23 ` [Xen-devel] " Anthony PERARD 2019-06-18 12:14 ` [Qemu-devel] " Daniel P. Berrangé 2019-06-18 12:14 ` [Xen-devel] " Daniel P. Berrangé 2019-06-20 14:44 ` Anthony PERARD 2019-06-20 14:44 ` [Xen-devel] " Anthony PERARD 2019-06-18 11:23 ` [Qemu-devel] [PATCH v2 2/4] xen: Import other xen/io/*.h Anthony PERARD 2019-06-18 11:23 ` [Xen-devel] " Anthony PERARD 2019-06-18 11:23 ` [Qemu-devel] [PATCH v2 3/4] xen: Drop includes of xen/hvm/params.h Anthony PERARD 2019-06-18 11:23 ` [Xen-devel] " Anthony PERARD 2019-06-18 11:51 ` [Qemu-devel] " Paul Durrant 2019-06-18 11:51 ` [Xen-devel] " Paul Durrant 2019-06-18 11:23 ` Anthony PERARD [this message] 2019-06-18 11:23 ` [Xen-devel] [PATCH v2 4/4] xen: Avoid VLA Anthony PERARD 2019-06-18 11:35 ` [Qemu-devel] " Philippe Mathieu-Daudé 2019-06-18 11:35 ` [Xen-devel] " Philippe Mathieu-Daudé 2019-06-18 11:52 ` Paul Durrant 2019-06-18 11:52 ` [Xen-devel] " Paul Durrant 2019-06-18 12:00 ` [Qemu-devel] [Xen-devel] [PATCH v2 0/4] Fix build of Xen support + cleanup no-reply 2019-06-18 12:00 ` no-reply
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