Fix "MOVS" instruction memory to MMIO emulation. Currently updates to

%rdi, %rsi, etc are inadvertently bypassed along with the check to
see if the instruction needs to be repeated per the 'rep' prefix.

Add "MOVS" instruction support for the 'MMIO to MMIO' case.

Reviewed by:	neel

1 files changed, 50 insertions, 31 deletions

diff --git a/sys/amd64/vmm/vmm_instruction_emul.c b/sys/amd64/vmm/vmm_instruction_emul.c
index 2dfbe8b..ca0b144 100644
--- a/sys/amd64/vmm/vmm_instruction_emul.c
+++ b/sys/amd64/vmm/vmm_instruction_emul.c
@@ -634,7 +634,7 @@ emulate_movs(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
 #else
 	struct iovec copyinfo[2];
 #endif
-	uint64_t dstaddr, srcaddr, val;
+	uint64_t dstaddr, srcaddr, dstgpa, srcgpa, val;
 	uint64_t rcx, rdi, rsi, rflags;
 	int error, opsize, seg, repeat;
 
@@ -669,7 +669,7 @@ emulate_movs(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
 	 * (1)  memory		memory		n/a
 	 * (2)  memory		mmio		emulated
 	 * (3)  mmio		memory		emulated
-	 * (4)  mmio		mmio		not emulated
+	 * (4)  mmio		mmio		emulated
 	 *
 	 * At this point we don't have sufficient information to distinguish
 	 * between (2), (3) and (4). We use 'vm_copy_setup()' to tease this
@@ -694,7 +694,8 @@ emulate_movs(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
 		vm_copyin(vm, vcpuid, copyinfo, &val, opsize);
 		vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
 		error = memwrite(vm, vcpuid, gpa, val, opsize, arg);
-		goto done;
+		if (error)
+			goto done;
 	} else if (error > 0) {
 		/*
 		 * Resume guest execution to handle fault.
@@ -705,37 +706,55 @@ emulate_movs(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
 		 * 'vm_copy_setup()' is expected to fail for cases (3) and (4)
 		 * if 'srcaddr' is in the mmio space.
 		 */
-	}
-
-	error = get_gla(vm, vcpuid, vie, paging, opsize, vie->addrsize,
-	    PROT_WRITE, VM_REG_GUEST_ES, VM_REG_GUEST_RDI, &dstaddr);
-	if (error)
-		goto done;
 
-	error = vm_copy_setup(vm, vcpuid, paging, dstaddr, opsize,
-	    PROT_WRITE, copyinfo, nitems(copyinfo));
-	if (error == 0) {
-		/*
-		 * case (3): read from MMIO and write to system memory.
-		 *
-		 * A MMIO read can have side-effects so we commit to it
-		 * only after vm_copy_setup() is successful. If a page-fault
-		 * needs to be injected into the guest then it will happen
-		 * before the MMIO read is attempted.
-		 */
-		error = memread(vm, vcpuid, gpa, &val, opsize, arg);
+		error = get_gla(vm, vcpuid, vie, paging, opsize, vie->addrsize,
+		    PROT_WRITE, VM_REG_GUEST_ES, VM_REG_GUEST_RDI, &dstaddr);
 		if (error)
 			goto done;
 
-		vm_copyout(vm, vcpuid, &val, copyinfo, opsize);
-		vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
-	} else if (error > 0) {
-		/*
-		 * Resume guest execution to handle fault.
-		 */
-		goto done;
-	} else {
-		goto done;
+		error = vm_copy_setup(vm, vcpuid, paging, dstaddr, opsize,
+		    PROT_WRITE, copyinfo, nitems(copyinfo));
+		if (error == 0) {
+			/*
+			 * case (3): read from MMIO and write to system memory.
+			 *
+			 * A MMIO read can have side-effects so we
+			 * commit to it only after vm_copy_setup() is
+			 * successful. If a page-fault needs to be
+			 * injected into the guest then it will happen
+			 * before the MMIO read is attempted.
+			 */
+			error = memread(vm, vcpuid, gpa, &val, opsize, arg);
+			if (error)
+				goto done;
+
+			vm_copyout(vm, vcpuid, &val, copyinfo, opsize);
+			vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
+		} else if (error > 0) {
+			/*
+			 * Resume guest execution to handle fault.
+			 */
+			goto done;
+		} else {
+			/*
+			 * Case (4): read from and write to mmio.
+			 */
+			error = vm_gla2gpa(vm, vcpuid, paging, srcaddr,
+			    PROT_READ, &srcgpa);
+			if (error)
+				goto done;
+			error = memread(vm, vcpuid, srcgpa, &val, opsize, arg);
+			if (error)
+				goto done;
+
+			error = vm_gla2gpa(vm, vcpuid, paging, dstaddr,
+			   PROT_WRITE, &dstgpa);
+			if (error)
+				goto done;
+			error = memwrite(vm, vcpuid, dstgpa, val, opsize, arg);
+			if (error)
+				goto done;
+		}
 	}
 
 	error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RSI, &rsi);
@@ -1465,7 +1484,7 @@ ptp_hold(struct vm *vm, vm_paddr_t ptpphys, size_t len, void **cookie)
 }
 
 int
-vmm_gla2gpa(struct vm *vm, int vcpuid, struct vm_guest_paging *paging,
+vm_gla2gpa(struct vm *vm, int vcpuid, struct vm_guest_paging *paging,
     uint64_t gla, int prot, uint64_t *gpa)
 {
 	int nlevels, pfcode, ptpshift, ptpindex, retval, usermode, writable;