Blame SOURCES/kvm-cirrus-handle-negative-pitch-in-cirrus_invalidate_re.patch

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From 45023277a5822c89806eae1cc5f4d5f897e28fcd Mon Sep 17 00:00:00 2001
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From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Tue, 7 Feb 2017 10:07:49 +0100
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Subject: [PATCH 06/11] cirrus: handle negative pitch in
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 cirrus_invalidate_region()
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RH-Author: Gerd Hoffmann <kraxel@redhat.com>
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Message-id: <1486462072-32174-5-git-send-email-kraxel@redhat.com>
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Patchwork-id: 73566
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O-Subject: [RHEL-7.4 qemu-kvm PATCH 4/7] cirrus: handle negative pitch in cirrus_invalidate_region()
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Bugzilla: 1418233
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RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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From: Wolfgang Bumiller <w.bumiller@proxmox.com>
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cirrus_invalidate_region() calls memory_region_set_dirty()
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on a per-line basis, always ranging from off_begin to
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off_begin+bytesperline. With a negative pitch off_begin
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marks the top most used address and thus we need to do an
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initial shift backwards by a line for negative pitches of
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backward blits, otherwise the first iteration covers the
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line going from the start offset forwards instead of
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backwards.
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Additionally since the start address is inclusive, if we
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shift by a full `bytesperline` we move to the first address
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*not* included in the blit, so we only shift by one less
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than bytesperline.
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Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
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Message-id: 1485352137-29367-1-git-send-email-w.bumiller@proxmox.com
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[ kraxel: codestyle fixes ]
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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(cherry picked from commit f153b563f8cf121aebf5a2fff5f0110faf58ccb3)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 hw/display/cirrus_vga.c | 5 +++++
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 1 file changed, 5 insertions(+)
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diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c
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index c8f2f26..e09076a 100644
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--- a/hw/display/cirrus_vga.c
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+++ b/hw/display/cirrus_vga.c
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@@ -656,9 +656,14 @@ static void cirrus_invalidate_region(CirrusVGAState * s, int off_begin,
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     int off_cur;
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     int off_cur_end;
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+    if (off_pitch < 0) {
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+        off_begin -= bytesperline - 1;
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+    }
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+
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     for (y = 0; y < lines; y++) {
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 	off_cur = off_begin;
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 	off_cur_end = (off_cur + bytesperline) & s->cirrus_addr_mask;
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+        assert(off_cur_end >= off_cur);
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         memory_region_set_dirty(&s->vga.vram, off_cur, off_cur_end - off_cur);
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 	off_begin += off_pitch;
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     }
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-- 
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1.8.3.1
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