virtio,pci,pc: features, fixes

[PULL 38/75] intel_iommu: Bypass barrier wait descriptor

Michael S. Tsirkin posted 75 patches 1 month, 1 week ago

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Maintainers: "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Dongjiu Geng <gengdongjiu1@gmail.com>, Stefano Garzarella <sgarzare@redhat.com>, Igor Mammedov <imammedo@redhat.com>, Ani Sinha <anisinha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Mauro Carvalho Chehab <mchehab+huawei@kernel.org>, Shannon Zhao <shannon.zhaosl@gmail.com>, Peter Maydell <peter.maydell@linaro.org>, Stefan Hajnoczi <stefanha@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Hanna Reitz <hreitz@redhat.com>, Eduardo Habkost <eduardo@habkost.net>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Yanan Wang <wangyanan55@huawei.com>, Zhao Liu <zhao1.liu@intel.com>, Richard Henderson <richard.henderson@linaro.org>, Jason Wang <jasowang@redhat.com>, Yi Liu <yi.l.liu@intel.com>, "Clément Mathieu--Drif" <clement.mathieu--drif@eviden.com>, Dmitry Fleytman <dmitry.fleytman@gmail.com>, Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>, Sriram Yagnaraman <sriram.yagnaraman@ericsson.com>, Keith Busch <kbusch@kernel.org>, Klaus Jensen <its@irrelevant.dk>, Jesper Devantier <foss@defmacro.it>, Fam Zheng <fam@euphon.net>, David Hildenbrand <david@redhat.com>, Cornelia Huck <cohuck@redhat.com>, Luigi Rizzo <rizzo@iet.unipi.it>, Giuseppe Lettieri <g.lettieri@iet.unipi.it>, Vincenzo Maffione <v.maffione@gmail.com>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>, Michael Roth <michael.roth@amd.com>, John Snow <jsnow@redhat.com>, Cleber Rosa <crosa@redhat.com>, Peter Xu <peterx@redhat.com>, Fabiano Rosas <farosas@suse.de>, Laurent Vivier <lvivier@redhat.com>

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[PULL 38/75] intel_iommu: Bypass barrier wait descriptor

Posted by Michael S. Tsirkin 1 month, 1 week ago

From: CLEMENT MATHIEU--DRIF <clement.mathieu--drif@eviden.com>

wait_desc with SW=0,IF=0,FN=1 must not be considered as an
invalid descriptor as it is used to implement section 7.10 of
the VT-d spec.

Signed-off-by: Clement Mathieu--Drif <clement.mathieu--drif@eviden.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20250901111630.1018573-3-clement.mathieu--drif@eviden.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/i386/intel_iommu.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 83c5e44413..4e7ad3a290 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -2857,7 +2857,13 @@ static bool vtd_process_wait_desc(IntelIOMMUState *s, VTDInvDesc *inv_desc)
         vtd_generate_completion_event(s);
     }
 
-    if (!(inv_desc->lo & (VTD_INV_DESC_WAIT_IF | VTD_INV_DESC_WAIT_SW))) {
+    /*
+     * SW=0, IF=0, FN=1 is also a valid descriptor (VT-d 7.10)
+     * Nothing to do as we process the descriptors in order
+     */
+
+    if (!(inv_desc->lo & (VTD_INV_DESC_WAIT_IF | VTD_INV_DESC_WAIT_SW |
+                                                 VTD_INV_DESC_WAIT_FN))) {
         error_report_once("%s: invalid wait desc: hi=%"PRIx64", lo=%"PRIx64
                           " (unknown type)", __func__, inv_desc->hi,
                           inv_desc->lo);
-- 
MST