KVM: x86: Document APIC base address constraint for in-kernel irqchip

Browse source

When virtual APIC access acceleration is enabled (APICv on Intel, AVIC
on AMD), vcpu creation installs a private memory slot at the default
APIC base address (0xfee00000).  If a user memory region overlaps this
address, vcpu creation fails with EEXIST.  The same error occurs when
installing an overlapping user memory region after vcpu creation.

This also applies when using KVM_CAP_SPLIT_IRQCHIP.

This constraint is not documented anywhere.  Add a note to the
KVM_CREATE_IRQCHIP and KVM_CAP_SPLIT_IRQCHIP documentation.

Signed-off-by: Tim Wiederhake <twiederh@redhat.com>
Link: https://patch.msgid.link/20260708133856.302151-3-twiederh@redhat.com
[sean: call out "subsequent vcpu creation"]
Signed-off-by: Sean Christopherson <seanjc@google.com>

...

This commit is contained in:

Tim Wiederhake 2026-07-08 15:38:55 +02:00 • committed by Sean Christopherson

parent d82d77c643

commit 99607da19b

1 changed files with 12 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

12

Documentation/virt/kvm/api.rst

View file