Blame SOURCES/kvm-ahci.c-mask-unused-flags-when-reading-size-PRDT-DBC.patch

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From e4edeb73e3b9b1ba4efbf18ddb687fb210fd57f8 Mon Sep 17 00:00:00 2001
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From: John Snow <jsnow@redhat.com>
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Date: Fri, 26 Jun 2015 21:52:46 +0200
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Subject: [PATCH 1/2] ahci.c: mask unused flags when reading size PRDT DBC
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Message-id: <1435355567-29641-2-git-send-email-jsnow@redhat.com>
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Patchwork-id: 66535
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O-Subject: [RHEL-7.2 qemu-kvm PATCH 1/2] ahci.c: mask unused flags when reading size PRDT DBC
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Bugzilla: 1205100
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Juan Quintela <quintela@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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From: Reza Jelveh <reza.jelveh@tuhh.de>
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The data byte count(DBC) read from the description information is defined for
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bits 21:00. Bits 30:22 are reserved and bit 31 is the Interrupt on Completion
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(I) flag.
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Completion interrupts are triggered after every transaction instead of on
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I-flag in QEMU. tbl_entry_size is a signed integer and improperly reading the
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DBC leads to a negative offset that causes sglist allocation to fail.
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Signed-off-by: Reza Jelveh <reza.jelveh@tuhh.de>
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Reviewed-by: Alexander Graf <agraf@suse.de>
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Reviewed-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: John Snow <jsnow@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit d02f8adc6d2a178bcbf77d0413f9a96fdbed53f0)
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Signed-off-by: John Snow <jsnow@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 hw/ide/ahci.c | 11 ++++++++---
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 hw/ide/ahci.h |  2 ++
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 2 files changed, 10 insertions(+), 3 deletions(-)
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diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
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index 011e796..7f3927a 100644
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--- a/hw/ide/ahci.c
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+++ b/hw/ide/ahci.c
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@@ -635,6 +635,11 @@ static void ahci_write_fis_d2h(AHCIDevice *ad, uint8_t *cmd_fis)
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     }
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 }
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+static int prdt_tbl_entry_size(const AHCI_SG *tbl)
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+{
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+    return (le32_to_cpu(tbl->flags_size) & AHCI_PRDT_SIZE_MASK) + 1;
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+}
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+
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 static int ahci_populate_sglist(AHCIDevice *ad, QEMUSGList *sglist, int offset)
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 {
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     AHCICmdHdr *cmd = ad->cur_cmd;
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@@ -675,7 +680,7 @@ static int ahci_populate_sglist(AHCIDevice *ad, QEMUSGList *sglist, int offset)
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         sum = 0;
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         for (i = 0; i < sglist_alloc_hint; i++) {
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             /* flags_size is zero-based */
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-            tbl_entry_size = (le32_to_cpu(tbl[i].flags_size) + 1);
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+            tbl_entry_size = prdt_tbl_entry_size(&tbl[i]);
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             if (offset <= (sum + tbl_entry_size)) {
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                 off_idx = i;
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                 off_pos = offset - sum;
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@@ -693,12 +698,12 @@ static int ahci_populate_sglist(AHCIDevice *ad, QEMUSGList *sglist, int offset)
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         qemu_sglist_init(sglist, (sglist_alloc_hint - off_idx), ad->hba->dma);
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         qemu_sglist_add(sglist, le64_to_cpu(tbl[off_idx].addr + off_pos),
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-                        le32_to_cpu(tbl[off_idx].flags_size) + 1 - off_pos);
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+                        prdt_tbl_entry_size(&tbl[off_idx]) - off_pos);
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         for (i = off_idx + 1; i < sglist_alloc_hint; i++) {
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             /* flags_size is zero-based */
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             qemu_sglist_add(sglist, le64_to_cpu(tbl[i].addr),
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-                            le32_to_cpu(tbl[i].flags_size) + 1);
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+                            prdt_tbl_entry_size(&tbl[i]));
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         }
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     }
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diff --git a/hw/ide/ahci.h b/hw/ide/ahci.h
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index 85f37fe..47c0961 100644
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--- a/hw/ide/ahci.h
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+++ b/hw/ide/ahci.h
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@@ -201,6 +201,8 @@
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 #define AHCI_COMMAND_TABLE_ACMD            0x40
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+#define AHCI_PRDT_SIZE_MASK                0x3fffff
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+
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 #define IDE_FEATURE_DMA                    1
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 #define READ_FPDMA_QUEUED                  0x60
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-- 
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1.8.3.1
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