[RFC,v2,4/5] KVM: X86: Add documentation about behavioral difference for KVM_EXIT_BUS_LOCK

Commit Message

Manali Shukla Oct. 1, 2024, 6:34 a.m. UTC

Add a note about behavioral difference for KVM_EXIT_X86_BUS_LOCK
between AMD CPUs and Intel CPUs in KVM_CAP_X86_BUS_LOCK_EXIT
capability documentation.

Signed-off-by: Manali Shukla <[e-mail]>
---
 Documentation/virt/kvm/api.rst | 5 +++++
 1 file changed, 5 insertions(+)

Patch

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index b3be87489108..536010e1df1d 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -7869,6 +7869,11 @@  Note! Detected bus locks may be coincident with other exits to userspace, i.e.
 KVM_RUN_X86_BUS_LOCK should be checked regardless of the primary exit reason if
 userspace wants to take action on all detected bus locks.
 
+Note! In KVM on AMD CPUs, the bus lock exit to user space occurs with RIP
+pointing at the offending instruction. In contrast, in KVM on Intel CPUs, the
+RIP points to the instruction right after the guilty one after the bus lock
+exit to user space.
+
 7.23 KVM_CAP_PPC_DAWR1
 ----------------------