KVM: APIC: avoid instruction emulation for EOI writes
Instruction emulation for EOI writes can be skipped, since sane
guest simply uses MOV instead of string operations. This is a nice
improvement when guest doesn't support x2apic or hyper-V EOI
support.
a single VM bandwidth is observed with ~8% bandwidth improvement
(7.4Gbps->8Gbps), by saving ~5% cycles from EOI emulation.
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
<Based on earlier work from>:
Signed-off-by: Eddie Dong <eddie.dong@intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 2caf290..31f180c 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -350,6 +350,18 @@
#define DEBUG_REG_ACCESS_REG(eq) (((eq) >> 8) & 0xf) /* 11:8, general purpose reg. */
+/*
+ * Exit Qualifications for APIC-Access
+ */
+#define APIC_ACCESS_OFFSET 0xfff /* 11:0, offset within the APIC page */
+#define APIC_ACCESS_TYPE 0xf000 /* 15:12, access type */
+#define TYPE_LINEAR_APIC_INST_READ (0 << 12)
+#define TYPE_LINEAR_APIC_INST_WRITE (1 << 12)
+#define TYPE_LINEAR_APIC_INST_FETCH (2 << 12)
+#define TYPE_LINEAR_APIC_EVENT (3 << 12)
+#define TYPE_PHYSICAL_APIC_EVENT (10 << 12)
+#define TYPE_PHYSICAL_APIC_INST (15 << 12)
+
/* segment AR */
#define SEGMENT_AR_L_MASK (1 << 13)