[tip: x86/apic] x86/kvm: Reserve KVM_FEATURE_MSI_EXT_DEST_ID

[tip-bot2 for David Woodhouse]

The following commit has been merged into the x86/apic branch of tip:

Commit-ID:     5a169bf04cd2bfdbac967d12eb5b70915b29d7ee
Gitweb:        https://git.kernel.org/tip/5a169bf04cd2bfdbac967d12eb5b70915b29d7ee
Author:        David Woodhouse <dwmw@xxxxxxxxxxxx>
AuthorDate:    Mon, 19 Oct 2020 15:55:56 +01:00
Committer:     Paolo Bonzini <pbonzini@xxxxxxxxxx>
CommitterDate: Wed, 28 Oct 2020 13:52:05 -04:00

x86/kvm: Reserve KVM_FEATURE_MSI_EXT_DEST_ID

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@xxxxxxxxxxxx>
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Message-Id: <4cd59bed05f4b7410d3d1ffd1e997ab53683874d.camel@xxxxxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
 Documentation/virt/kvm/cpuid.rst     | 4 ++++
 arch/x86/include/uapi/asm/kvm_para.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/Documentation/virt/kvm/cpuid.rst b/Documentation/virt/kvm/cpuid.rst
index 7d81c0a..cf62162 100644
--- a/Documentation/virt/kvm/cpuid.rst
+++ b/Documentation/virt/kvm/cpuid.rst
@@ -92,6 +92,10 @@ KVM_FEATURE_ASYNC_PF_INT           14          guest checks this feature bit
                                                async pf acknowledgment msr
                                                0x4b564d07.
 
+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
diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
index 812e9b4..950afeb 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -32,6 +32,7 @@
 #define KVM_FEATURE_POLL_CONTROL	12
 #define KVM_FEATURE_PV_SCHED_YIELD	13
 #define KVM_FEATURE_ASYNC_PF_INT	14
+#define KVM_FEATURE_MSI_EXT_DEST_ID	15
 
 #define KVM_HINTS_REALTIME      0