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* Tue Aug 11 2026 Miroslav Rezanina <mrezanin@redhat.com> - 10.1.0-26

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- kvm-vfio-region-Clarify-dma-buf-failure-messages.patch [RHEL-224652]
- Resolves: RHEL-224652
  (Backport  vfio/region: Clarify dma-buf failure messages )
This commit is contained in:
Miroslav Rezanina 2026-08-11 09:56:28 +02:00
parent 15aa0bf413
commit a0326fabe8
2 changed files with 75 additions and 1 deletions
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67
kvm-vfio-region-Clarify-dma-buf-failure-messages.patch Normal file
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@ -0,0 +1,67 @@
From c5a8a9187f8395f35218cb6e301ee777f4a0da7b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= <clg@redhat.com>
Date: Wed, 15 Jul 2026 10:00:00 +0200
Subject: [PATCH] vfio/region: Clarify dma-buf failure messages
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
RH-Author: Rodolfo Vick <None>
RH-MergeRequest: 514: vfio/region: Clarify dma-buf failure messages
RH-Jira: RHEL-224652
RH-Acked-by: Cédric Le Goater <clg@redhat.com>
RH-Acked-by: Eric Auger <eric.auger@redhat.com>
RH-Commit: [1/1] 290b4b792bd444608b01bab64514a0e0725e9f89 (rovick1/qemu-kvm)
The dma-buf failure messages in vfio_region_create_dma_buf() say "PCI
BAR IOMMU mappings may fail", which suggests the BAR is broken. In
practice, only P2P DMA is affected -- normal passthrough uses the mmap
fallback.
Reword both messages to mention P2P DMA explicitly and clarify that
the mmap fallback is in use. Use warn_report_err_once() at the call
site so per-BAR repetition on mdev devices is suppressed.
Fixes: dcf1b77e834d ("hw/vfio/region: Create dmabuf for PCI BAR per region")
Cc: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
(cherry picked from commit 4b2e6505d59b7b16c6e15a2494942d00648e8510)
---
hw/vfio/region.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/hw/vfio/region.c b/hw/vfio/region.c
index 1e9915fdd3..9258ab6847 100644
--- a/hw/vfio/region.c
+++ b/hw/vfio/region.c
@@ -316,13 +316,12 @@ static bool vfio_region_create_dma_buf(VFIORegion *region, Error **errp)
ret = vfio_device_get_feature(vbasedev, feature);
if (ret < 0) {
if (ret == -ENOTTY) {
- warn_report_once("VFIO dma-buf not supported in kernel: "
- "PCI BAR IOMMU mappings may fail");
+ warn_report_once("VFIO dma-buf not supported in kernel, "
+ "using mmap fallback, P2P DMA will not work");
return true;
}
- /* P2P DMA or exposing device memory use cases are not supported. */
- error_setg_errno(errp, -ret, "%s: failed to create dma-buf: "
- "PCI BAR IOMMU mappings may fail",
+ error_setg_errno(errp, -ret, "%s: dma-buf unavailable, "
+ "using mmap fallback, P2P DMA will not work",
memory_region_name(region->mem));
return false;
}
@@ -443,7 +442,7 @@ int vfio_region_mmap(VFIORegion *region)
}
if (!vfio_region_create_dma_buf(region, &local_err)) {
- error_report_err(local_err);
+ warn_report_err_once(local_err);
}
return 0;
--
2.52.0

9
qemu-kvm.spec
View File

@ -143,7 +143,7 @@ Obsoletes: %{name}-block-ssh <= %{epoch}:%{version} \
Summary: QEMU is a machine emulator and virtualizer
Name: qemu-kvm
Version: 10.1.0
Release: 25%{?rcrel}%{?dist}%{?cc_suffix}
Release: 26%{?rcrel}%{?dist}%{?cc_suffix}
# Epoch because we pushed a qemu-1.0 package. AIUI this can't ever be dropped
# Epoch 15 used for RHEL 8
# Epoch 17 used for RHEL 9 (due to release versioning offset in RHEL 8.5)
@ -1672,6 +1672,8 @@ Patch477: kvm-s390x-sclp-prevent-re-reading-the-sclp-header.patch
Patch478: kvm-s390x-sclpcpi-check-event-length-field-before-readin.patch
# For RHEL-192791 - RHEL10.0 - qemu s390x: interface harding fixes
Patch479: kvm-s390x-css-firm-up-handling-of-chained-TIC-CCWs.patch
# For RHEL-224652 - Backport vfio/region: Clarify dma-buf failure messages
Patch480: kvm-vfio-region-Clarify-dma-buf-failure-messages.patch
%if %{have_clang}
BuildRequires: clang
@ -2754,6 +2756,11 @@ useradd -r -u 107 -g qemu -G kvm -d / -s /sbin/nologin \
%endif
%changelog
* Tue Aug 11 2026 Miroslav Rezanina <mrezanin@redhat.com> - 10.1.0-26
- kvm-vfio-region-Clarify-dma-buf-failure-messages.patch [RHEL-224652]
- Resolves: RHEL-224652
(Backport vfio/region: Clarify dma-buf failure messages )
* Mon Aug 03 2026 Miroslav Rezanina <mrezanin@redhat.com> - 10.1.0-25
- kvm-hw-core-platform-bus-guard-platform_bus_get_mmio_add.patch [RHEL-180837]
- kvm-hw-tpm-gate-PPI-support-on-tpm-tis-device-behind-a-d.patch [RHEL-180837]