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#1181001, 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/virtual/kvm/cpuid.txt | 4 ++++
arch/x86/include/uapi/asm/kvm_para.h | 1 +
2 files changed, 5 insertions(+)
--- a/Documentation/virtual/kvm/cpuid.txt
+++ b/Documentation/virtual/kvm/cpuid.txt
@@ -58,6 +58,10 @@ KVM_FEATURE_ASYNC_PF_VMEXIT ||
|| || can be enabled by setting bit 2
|| || when writing to msr 0x4b564d02
------------------------------------------------------------------------------
+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_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side
|| || per-cpu warps are expected in
|| || kvmclock.
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -24,6 +24,7 @@
#define KVM_FEATURE_PV_EOI 6
#define KVM_FEATURE_PV_UNHALT 7
#define KVM_FEATURE_ASYNC_PF_VMEXIT 10
+#define KVM_FEATURE_MSI_EXT_DEST_ID 15
/* The last 8 bits are used to indicate how to interpret the flags field
* in pvclock structure. If no bits are set, all flags are ignored.