From: David Woodhouse <dwmw@amazon.co.uk>
Date: Mon, 19 Oct 2020 15:55:56 +0100
Subject: x86/kvm: Reserve KVM_FEATURE_MSI_EXT_DEST_ID
Git-commit: 5a169bf04cd2bfdbac967d12eb5b70915b29d7ee
Patch-mainline: v5.10-rc2
References: bsc#1181259 jsc#ECO-3191

No functional change; just reserve the feature bit for now so that VMMs
can start to implement it.

This will allow the host to indicate that MSI emulation supports 15-bit
destination IDs, allowing up to 32768 CPUs without interrupt remapping.

cf. https://patchwork.kernel.org/patch/11816693/ for qemu

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <4cd59bed05f4b7410d3d1ffd1e997ab53683874d.camel@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
 Documentation/virt/kvm/cpuid.rst     |    4 ++++
 arch/x86/include/uapi/asm/kvm_para.h |    1 +
 2 files changed, 5 insertions(+)

--- a/Documentation/virt/kvm/cpuid.rst
+++ b/Documentation/virt/kvm/cpuid.rst
@@ -86,6 +86,10 @@ KVM_FEATURE_PV_SCHED_YIELD        13
                                               before using paravirtualized
                                               sched yield.
 
+KVM_FEATURE_MSI_EXT_DEST_ID       15          guest checks this feature bit
+                                              before using extended destination
+                                              ID bits in MSI address bits 11-5.
+
 KVM_FEATURE_CLOCSOURCE_STABLE_BIT 24          host will warn if no guest-side
                                               per-cpu warps are expeced in
                                               kvmclock
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -31,6 +31,7 @@
 #define KVM_FEATURE_PV_SEND_IPI	11
 #define KVM_FEATURE_POLL_CONTROL	12
 #define KVM_FEATURE_PV_SCHED_YIELD	13
+#define KVM_FEATURE_MSI_EXT_DEST_ID	15
 
 #define KVM_HINTS_REALTIME      0