svn commit: r339331 - head/sys/amd64/vmm

[Konstantin Belousov]

Author: kib
Date: Fri Oct 12 15:30:15 2018
New Revision: 339331
URL: https://svnweb.freebsd.org/changeset/base/339331

Log:
  bhyve: emulate CLFLUSH and CLFLUSHOPT.
  
  Apparently CLFLUSH on mmio can cause VM exit, as reported in the PR.
  I do not see that anything useful can be done except emulating page
  faults on invalid addresses.
  
  Due to the instruction encoding pecularity, also emulate SFENCE.
  
  PR:	232081
  Reported by:	phk
  Reviewed by:	araujo, avg, jhb (all: previous version)
  Sponsored by:	The FreeBSD Foundation
  Approved by:	re (gjb)
  MFC after:	1 week
  Differential revision:	https://reviews.freebsd.org/D17482

Modified:
  head/sys/amd64/vmm/vmm_instruction_emul.c

Modified: head/sys/amd64/vmm/vmm_instruction_emul.c
==============================================================================
--- head/sys/amd64/vmm/vmm_instruction_emul.c	Fri Oct 12 15:19:41 2018	(r339330)
+++ head/sys/amd64/vmm/vmm_instruction_emul.c	Fri Oct 12 15:30:15 2018	(r339331)
@@ -76,6 +76,7 @@ enum {
 	VIE_OP_TYPE_GROUP1,
 	VIE_OP_TYPE_STOS,
 	VIE_OP_TYPE_BITTEST,
+	VIE_OP_TYPE_TWOB_GRP15,
 	VIE_OP_TYPE_LAST
 };
 
@@ -87,6 +88,10 @@ enum {
 #define	VIE_OP_F_NO_GLA_VERIFICATION (1 << 4)
 
 static const struct vie_op two_byte_opcodes[256] = {
+	[0xAE] = {
+		  .op_byte = 0xAE,
+		  .op_type = VIE_OP_TYPE_TWOB_GRP15,
+	},
 	[0xB6] = {
 		.op_byte = 0xB6,
 		.op_type = VIE_OP_TYPE_MOVZX,
@@ -1443,6 +1448,37 @@ emulate_bittest(void *vm, int vcpuid, uint64_t gpa, st
 	return (0);
 }
 
+static int
+emulate_twob_group15(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
+    mem_region_read_t memread, mem_region_write_t memwrite, void *memarg)
+{
+	int error;
+	uint64_t buf;
+
+	switch (vie->reg & 7) {
+	case 0x7:	/* CLFLUSH, CLFLUSHOPT, and SFENCE */
+		if (vie->mod == 0x3) {
+			/*
+			 * SFENCE.  Ignore it, VM exit provides enough
+			 * barriers on its own.
+			 */
+			error = 0;
+		} else {
+			/*
+			 * CLFLUSH, CLFLUSHOPT.  Only check for access
+			 * rights.
+			 */
+			error = memread(vm, vcpuid, gpa, &buf, 1, memarg);
+		}
+		break;
+	default:
+		error = EINVAL;
+		break;
+	}
+
+	return (error);
+}
+
 int
 vmm_emulate_instruction(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
     struct vm_guest_paging *paging, mem_region_read_t memread,
@@ -1501,6 +1537,10 @@ vmm_emulate_instruction(void *vm, int vcpuid, uint64_t
 		break;
 	case VIE_OP_TYPE_BITTEST:
 		error = emulate_bittest(vm, vcpuid, gpa, vie,
+		    memread, memwrite, memarg);
+		break;
+	case VIE_OP_TYPE_TWOB_GRP15:
+		error = emulate_twob_group15(vm, vcpuid, gpa, vie,
 		    memread, memwrite, memarg);
 		break;
 	default: