Use lapic_ipi_alloc() to dynamically allocate IPI slots needed by bhyve when

vmm.ko is loaded.

Also relocate the 'justreturn' IPI handler to be alongside all other handlers.

Requested by:	kib

10 files changed, 40 insertions, 184 deletions

diff --git a/sys/amd64/amd64/apic_vector.S b/sys/amd64/amd64/apic_vector.S
index d9f2724..c3aac33 100644
--- a/sys/amd64/amd64/apic_vector.S
+++ b/sys/amd64/amd64/apic_vector.S
@@ -301,4 +301,35 @@ IDTVEC(rendezvous)
 	call	smp_rendezvous_action
 	call	as_lapic_eoi
 	jmp	doreti
+
+/*
+ * IPI handler whose purpose is to interrupt the CPU with minimum overhead.
+ * This is used by bhyve to force a host cpu executing in guest context to
+ * trap into the hypervisor.
+ *
+ * This handler is different from other IPI handlers in the following aspects:
+ *
+ * 1. It doesn't push a trapframe on the stack.
+ *
+ * This implies that a DDB backtrace involving 'justreturn' will skip the
+ * function that was interrupted by this handler.
+ *
+ * 2. It doesn't 'swapgs' when userspace is interrupted.
+ *
+ * The 'justreturn' handler does not access any pcpu data so it is not an
+ * issue. Moreover the 'justreturn' handler can only be interrupted by an NMI
+ * whose handler already doesn't trust GS.base when kernel code is interrupted.
+ */
+	.text
+	SUPERALIGN_TEXT
+IDTVEC(justreturn)
+	pushq	%rax
+	pushq	%rcx
+	pushq	%rdx
+	call	as_lapic_eoi
+	popq	%rdx
+	popq	%rcx
+	popq	%rax
+	jmp	doreti_iret
+
 #endif /* SMP */
diff --git a/sys/amd64/include/smp.h b/sys/amd64/include/smp.h
index 99bf1e4..3a4b6b3 100644
--- a/sys/amd64/include/smp.h
+++ b/sys/amd64/include/smp.h
@@ -54,6 +54,7 @@ inthand_t
 	IDTVEC(ipi_intr_bitmap_handler), /* Bitmap based IPIs */ 
 	IDTVEC(cpustop),	/* CPU stops & waits to be restarted */
 	IDTVEC(cpususpend),	/* CPU suspends & waits to be resumed */
+	IDTVEC(justreturn),	/* interrupt CPU with minimum overhead */
 	IDTVEC(rendezvous);	/* handle CPU rendezvous */
 
 struct pmap;
diff --git a/sys/amd64/vmm/intel/ept.c b/sys/amd64/vmm/intel/ept.c
index 13c9788..54320cb 100644
--- a/sys/amd64/vmm/intel/ept.c
+++ b/sys/amd64/vmm/intel/ept.c
@@ -43,7 +43,6 @@ __FBSDID("$FreeBSD$");
 #include <machine/vmm.h>
 
 #include "vmx_cpufunc.h"
-#include "vmm_ipi.h"
 #include "ept.h"
 
 #define	EPT_SUPPORTS_EXEC_ONLY(cap)	((cap) & (1UL << 0))
diff --git a/sys/amd64/vmm/intel/vmx.c b/sys/amd64/vmm/intel/vmx.c
index b81e48b..6dbf38a 100644
--- a/sys/amd64/vmm/intel/vmx.c
+++ b/sys/amd64/vmm/intel/vmx.c
@@ -55,7 +55,6 @@ __FBSDID("$FreeBSD$");
 #include "vmm_lapic.h"
 #include "vmm_host.h"
 #include "vmm_ioport.h"
-#include "vmm_ipi.h"
 #include "vmm_ktr.h"
 #include "vmm_stat.h"
 #include "vatpic.h"
@@ -175,7 +174,7 @@ static int posted_interrupts;
 SYSCTL_INT(_hw_vmm_vmx_cap, OID_AUTO, posted_interrupts, CTLFLAG_RD,
     &posted_interrupts, 0, "APICv posted interrupt support");
 
-static int pirvec;
+static int pirvec = -1;
 SYSCTL_INT(_hw_vmm_vmx, OID_AUTO, posted_interrupt_vector, CTLFLAG_RD,
     &pirvec, 0, "APICv posted interrupt vector");
 
@@ -485,8 +484,8 @@ static int
 vmx_cleanup(void)
 {
 	
-	if (pirvec != 0)
-		vmm_ipi_free(pirvec);
+	if (pirvec >= 0)
+		lapic_ipi_free(pirvec);
 
 	if (vpid_unr != NULL) {
 		delete_unrhdr(vpid_unr);
@@ -694,8 +693,8 @@ vmx_init(int ipinum)
 		    MSR_VMX_TRUE_PINBASED_CTLS, PINBASED_POSTED_INTERRUPT, 0,
 		    &tmp);
 		if (error == 0) {
-			pirvec = vmm_ipi_alloc();
-			if (pirvec == 0) {
+			pirvec = lapic_ipi_alloc(&IDTVEC(justreturn));
+			if (pirvec < 0) {
 				if (bootverbose) {
 					printf("vmx_init: unable to allocate "
 					    "posted interrupt vector\n");
diff --git a/sys/amd64/vmm/io/vlapic.c b/sys/amd64/vmm/io/vlapic.c
index b192735..7097248 100644
--- a/sys/amd64/vmm/io/vlapic.c
+++ b/sys/amd64/vmm/io/vlapic.c
@@ -45,7 +45,6 @@ __FBSDID("$FreeBSD$");
 
 #include <machine/vmm.h>
 
-#include "vmm_ipi.h"
 #include "vmm_lapic.h"
 #include "vmm_ktr.h"
 #include "vmm_stat.h"
diff --git a/sys/amd64/vmm/vmm.c b/sys/amd64/vmm/vmm.c
index 9e44549..7e72b02 100644
--- a/sys/amd64/vmm/vmm.c
+++ b/sys/amd64/vmm/vmm.c
@@ -76,7 +76,6 @@ __FBSDID("$FreeBSD$");
 #include "vlapic.h"
 #include "vpmtmr.h"
 #include "vrtc.h"
-#include "vmm_ipi.h"
 #include "vmm_stat.h"
 #include "vmm_lapic.h"
 
@@ -298,8 +297,8 @@ vmm_init(void)
 
 	vmm_host_state_init();
 
-	vmm_ipinum = vmm_ipi_alloc();
-	if (vmm_ipinum == 0)
+	vmm_ipinum = lapic_ipi_alloc(&IDTVEC(justreturn));
+	if (vmm_ipinum < 0)
 		vmm_ipinum = IPI_AST;
 
 	error = vmm_mem_init();
@@ -338,7 +337,7 @@ vmm_handler(module_t mod, int what, void *arg)
 			vmm_resume_p = NULL;
 			iommu_cleanup();
 			if (vmm_ipinum != IPI_AST)
-				vmm_ipi_free(vmm_ipinum);
+				lapic_ipi_free(vmm_ipinum);
 			error = VMM_CLEANUP();
 			/*
 			 * Something bad happened - prevent new
diff --git a/sys/amd64/vmm/vmm_ipi.c b/sys/amd64/vmm/vmm_ipi.c
deleted file mode 100644
index aefa3ba..0000000
--- a/sys/amd64/vmm/vmm_ipi.c
+++ /dev/null
@@ -1,93 +0,0 @@
-/*-
- * Copyright (c) 2011 NetApp, Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * $FreeBSD$
- */
-
-#include <sys/cdefs.h>
-__FBSDID("$FreeBSD$");
-
-#include <sys/param.h>
-#include <sys/systm.h>
-#include <sys/proc.h>
-#include <sys/bus.h>
-
-#include <machine/intr_machdep.h>
-#include <x86/apicvar.h>
-#include <machine/segments.h>
-#include <machine/md_var.h>
-
-#include <machine/vmm.h>
-#include "vmm_ipi.h"
-
-extern inthand_t IDTVEC(rsvd), IDTVEC(justreturn);
-
-CTASSERT(APIC_SPURIOUS_INT == 255);
-
-int
-vmm_ipi_alloc(void)
-{
-	int idx;
-	uintptr_t func;
-	struct gate_descriptor *ip;
-
-	/*
-	 * Search backwards from the highest IDT vector available for use
-	 * as our IPI vector. We install the 'justreturn' handler at that
-	 * vector and use it to interrupt the vcpus.
-	 *
-	 * We do this because the IPI_AST is heavyweight and saves all
-	 * registers in the trapframe. This is overkill for our use case
-	 * which is simply to EOI the interrupt and return.
-	 */
-	idx = APIC_SPURIOUS_INT;
-	while (--idx >= APIC_IPI_INTS) {
-		ip = &idt[idx];
-		func = ((long)ip->gd_hioffset << 16 | ip->gd_looffset);
-		if (func == (uintptr_t)&IDTVEC(rsvd)) {
-			setidt(idx , IDTVEC(justreturn), SDT_SYSIGT,
-			       SEL_KPL, 0);
-			return (idx);
-		}
-	}
-	return (0);
-}
-
-void
-vmm_ipi_free(int ipinum)
-{
-	uintptr_t func;
-	struct gate_descriptor *ip;
-
-	KASSERT(ipinum >= APIC_IPI_INTS && ipinum < APIC_SPURIOUS_INT,
-	    ("invalid ipi %d", ipinum));
-
-	ip = &idt[ipinum];
-	func = ((long)ip->gd_hioffset << 16 | ip->gd_looffset);
-	KASSERT(func == (uintptr_t)&IDTVEC(justreturn),
-	    ("invalid ipi %d", ipinum));
-
-	setidt(ipinum, IDTVEC(rsvd), SDT_SYSIGT, SEL_KPL, 0);
-}
diff --git a/sys/amd64/vmm/vmm_ipi.h b/sys/amd64/vmm/vmm_ipi.h
deleted file mode 100644
index 679d183..0000000
--- a/sys/amd64/vmm/vmm_ipi.h
+++ /dev/null
@@ -1,35 +0,0 @@
-/*-
- * Copyright (c) 2011 NetApp, Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * $FreeBSD$
- */
-
-#ifndef _VMM_IPI_H_
-#define _VMM_IPI_H_
-
-int	vmm_ipi_alloc(void);
-void	vmm_ipi_free(int num);
-
-#endif
diff --git a/sys/amd64/vmm/vmm_lapic.c b/sys/amd64/vmm/vmm_lapic.c
index fa9832e..15a995e 100644
--- a/sys/amd64/vmm/vmm_lapic.c
+++ b/sys/amd64/vmm/vmm_lapic.c
@@ -37,7 +37,6 @@ __FBSDID("$FreeBSD$");
 #include <x86/apicreg.h>
 
 #include <machine/vmm.h>
-#include "vmm_ipi.h"
 #include "vmm_ktr.h"
 #include "vmm_lapic.h"
 #include "vlapic.h"
diff --git a/sys/amd64/vmm/vmm_support.S b/sys/amd64/vmm/vmm_support.S
deleted file mode 100644
index 7919511..0000000
--- a/sys/amd64/vmm/vmm_support.S
+++ /dev/null
@@ -1,43 +0,0 @@
-/*-
- * Copyright (c) 2011 NetApp, Inc.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * $FreeBSD$
- */
-
-#define	LOCORE
-
-#include <machine/asmacros.h>
-
-	.text
-	SUPERALIGN_TEXT
-IDTVEC(justreturn)
-	pushq	%rdx
-	pushq	%rax
-	pushq	%rcx
-	call	as_lapic_eoi
-	popq	%rcx
-	popq	%rax
-	popq	%rdx
-	jmp	doreti_iret