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[PATCH v1 26/28] docs: add coverage for svm_avic=
- To: xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: dmukhin@xxxxxxxx
- Date: Wed, 4 Nov 2026 17:33:43 -0800
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- Cc: andrew.cooper3@xxxxxxxxxx, jason.andryuk@xxxxxxx, jbeulich@xxxxxxxx, roger@xxxxxxxxxxxxxx, teddy.astie@xxxxxxxxxx, dmukhin@xxxxxxx, Denis Mukhin <dmukhin@xxxxxxxx>
- Delivery-date: Thu, 05 Nov 2026 01:35:20 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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From: Denis Mukhin <dmukhin@xxxxxxxx>
Document new command line switch to enable/disable SVM AVIC driver
in the hypervisor.
Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
---
docs/misc/xen-command-line.pandoc | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/docs/misc/xen-command-line.pandoc
b/docs/misc/xen-command-line.pandoc
index a6f08463d177..e810f8836fe7 100644
--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -1623,7 +1623,7 @@ boolean (e.g. `iommu=no`) can override this and leave the
IOMMUs disabled.
This option depends on `intremap`, and is disabled by default due to some
corner cases in the implementation which have yet to be resolved.
- This option is only valid on x86, and only builds of Xen with HVM support.
+ This option is only valid on Intel x86, and only builds of Xen with HVM
support.
* The `crash-disable` boolean controls disabling IOMMU functionality
(DMAR/IR/QI)
before switching to a crash kernel. This option is inactive by default and
@@ -2673,6 +2673,27 @@ On Sappire and Emerald Rapids CPUs with May 2025
microcode or later, the
`ibpb-alt=` option can be used to switch to the alternative mitigation for
Intel SA-00982. Intel suggest that some workloads will benefit from this.
+### svm_avic (x86)
+> `= true | false | nodoorbell`
+
+This option configures Advanced Virtual Interrupt Controller (AVIC), which
+is an extension of AMD Secure Virtual Machine (SVM) to virtualize local APIC
+for guest VM.
+
+This parameter is experimental and for expert configuration only.
+
+Xen has mitigatations for the following AVIC hardware flaws:
+
+ * AMD Erratum 1235. A hardware flaw affecting certain AMD Family 17h and
+ Hygon Family 18h processors where the CPU hardware reads a stale
+ `IsRunning=1` bit during Interrupt Control Register (ICR) write emulation.
+
+Limitations:
+
+ * AVIC in x2APIC mode is not supported.
+
+ * AVIC in nested virtualization setup is not supported.
+
### sync_console
> `= <boolean>`
--
2.55.0
|
