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.