Re-arrange bits in the amd64/pmap 'pm_flags' field.

The least significant 8 bits of 'pm_flags' are now used for the IPI vector
to use for nested page table TLB shootdown.

Previously we used IPI_AST to interrupt the host cpu which is functionally
correct but could lead to misleading interrupt counts for AST handler. The
AST handler was also doing a lot more than what is required for the nested
page table TLB shootdown (EOI and IRET).

3 files changed, 10 insertions, 7 deletions

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index d60cbd1..014020b 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -1295,6 +1295,7 @@ pmap_invalidate_page_pcid(pmap_t pmap, vm_offset_t va)
 static __inline void
 pmap_invalidate_ept(pmap_t pmap)
 {
+	int ipinum;
 
 	sched_pin();
 	KASSERT(!CPU_ISSET(curcpu, &pmap->pm_active),
@@ -1319,11 +1320,9 @@ pmap_invalidate_ept(pmap_t pmap)
 
 	/*
 	 * Force the vcpu to exit and trap back into the hypervisor.
-	 *
-	 * XXX this is not optimal because IPI_AST builds a trapframe
-	 * whereas all we need is an 'eoi' followed by 'iret'.
 	 */
-	ipi_selected(pmap->pm_active, IPI_AST);
+	ipinum = pmap->pm_flags & PMAP_NESTED_IPIMASK;
+	ipi_selected(pmap->pm_active, ipinum);
 	sched_unpin();
 }
 
diff --git a/sys/amd64/include/pmap.h b/sys/amd64/include/pmap.h
index 01de629..3918282 100644
--- a/sys/amd64/include/pmap.h
+++ b/sys/amd64/include/pmap.h
@@ -312,9 +312,10 @@ struct pmap {
 };
 
 /* flags */
-#define	PMAP_PDE_SUPERPAGE	(1 << 0)	/* supports 2MB superpages */
-#define	PMAP_EMULATE_AD_BITS	(1 << 1)	/* needs A/D bits emulation */
-#define	PMAP_SUPPORTS_EXEC_ONLY	(1 << 2)	/* execute only mappings ok */
+#define	PMAP_NESTED_IPIMASK	0xff
+#define	PMAP_PDE_SUPERPAGE	(1 << 8)	/* supports 2MB superpages */
+#define	PMAP_EMULATE_AD_BITS	(1 << 9)	/* needs A/D bits emulation */
+#define	PMAP_SUPPORTS_EXEC_ONLY	(1 << 10)	/* execute only mappings ok */
 
 typedef struct pmap	*pmap_t;
 
diff --git a/sys/amd64/vmm/intel/ept.c b/sys/amd64/vmm/intel/ept.c
index 18e90f3..d68b7f9 100644
--- a/sys/amd64/vmm/intel/ept.c
+++ b/sys/amd64/vmm/intel/ept.c
@@ -43,6 +43,7 @@ __FBSDID("$FreeBSD$");
 #include <machine/vmm.h>
 
 #include "vmx_cpufunc.h"
+#include "vmm_ipi.h"
 #include "vmx_msr.h"
 #include "ept.h"
 
@@ -98,6 +99,8 @@ ept_init(void)
 	    !INVEPT_ALL_TYPES_SUPPORTED(cap))
 		return (EINVAL);
 
+	ept_pmap_flags = vmm_ipinum & PMAP_NESTED_IPIMASK;
+
 	use_superpages = 1;
 	TUNABLE_INT_FETCH("hw.vmm.ept.use_superpages", &use_superpages);
 	if (use_superpages && EPT_PDE_SUPERPAGE(cap))