git: 2919a487021a - stable/14 - bhyve x86: when accessing non-backed gpa, emulate hw

The branch stable/14 has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=2919a487021a7785bca1c1b059413a26286fe620

commit 2919a487021a7785bca1c1b059413a26286fe620
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2025-05-04 17:01:20 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2025-05-22 03:25:30 +0000

    bhyve x86: when accessing non-backed gpa, emulate hw
    
    PR:     286467
    
    (cherry picked from commit d8c4c2ce68eec8bac4e5cd0d133b8342e7a7f05d)
---
 usr.sbin/bhyve/amd64/Makefile.inc |  2 +-
 usr.sbin/bhyve/amd64/mem_x86.c    | 82 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 83 insertions(+), 1 deletion(-)

diff --git a/usr.sbin/bhyve/amd64/Makefile.inc b/usr.sbin/bhyve/amd64/Makefile.inc
index f8103ae1be32..851e64d154fa 100644
--- a/usr.sbin/bhyve/amd64/Makefile.inc
+++ b/usr.sbin/bhyve/amd64/Makefile.inc
@@ -7,7 +7,7 @@ SRCS+=	\
 	inout.c		\
 	ioapic.c	\
 	kernemu_dev.c	\
-	mem_md.c	\
+	mem_x86.c	\
 	mptbl.c		\
 	pci_ahci.c	\
 	pci_e82545.c	\
diff --git a/usr.sbin/bhyve/amd64/mem_x86.c b/usr.sbin/bhyve/amd64/mem_x86.c
new file mode 100644
index 000000000000..742d827db47f
--- /dev/null
+++ b/usr.sbin/bhyve/amd64/mem_x86.c
@@ -0,0 +1,82 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2025 The FreeBSD Foundation
+ *
+ * This software was developed by Konstantin Belousov <kib@FreeBSD.org>
+ * under sponsorship from the FreeBSD Foundation.
+ *
+ * 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 THE AUTHOR AND CONTRIBUTORS ``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 THE AUTHOR 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.
+ */
+
+#include <sys/types.h>
+#include <sys/errno.h>
+#include <sys/tree.h>
+#include <machine/vmm.h>
+
+#include <stdio.h>
+
+#include "debug.h"
+#include "mem.h"
+
+static int
+no_mem_handler(struct vcpu *vcpu __unused, int dir, uint64_t addr __unused,
+    int size, uint64_t *val, void *arg1 __unused, long arg2 __unused)
+{
+	if (dir == MEM_F_READ) {
+		switch (size) {
+		case 1:
+			*val = 0xff;
+			break;
+		case 2:
+			*val = 0xffff;
+			break;
+		case 4:
+			*val = 0xffffffff;
+			break;
+		case 8:
+			*val = 0xffffffffffffffff;
+			break;
+		}
+	}
+	return (0);
+}
+
+static struct mem_range fb_entry = {
+	.handler = no_mem_handler,
+	.base = 0,
+	.size = 0xffffffffffffffff,
+};
+
+/*
+ * x86 hardware ignores writes without receiver, and returns all 1's
+ * from reads without response to transaction.
+ */
+int
+mmio_handle_non_backed_mem(struct vcpu *vcpu __unused, uint64_t paddr,
+    struct mem_range **mr_paramp)
+{
+	*mr_paramp = &fb_entry;
+	EPRINTLN("Emulating access to non-existent address to %#lx\n",
+	    paddr);
+	return (0);
+}