[PATCH v4 kvmtool 07/12] Don't allow more than one framebuffers

From: Alexandru Elisei <alexandru.elisei@arm.com>
To: kvm@vger.kernel.org
Cc: will@kernel.org, julien.thierry.kdev@gmail.com,
	andre.przywara@arm.com, sami.mujawar@arm.com,
	lorenzo.pieralisi@arm.com, maz@kernel.org
Subject: [PATCH v4 kvmtool 07/12] Don't allow more than one framebuffers
Date: Thu, 14 May 2020 16:38:24 +0100	[thread overview]
Message-ID: <1589470709-4104-8-git-send-email-alexandru.elisei@arm.com> (raw)
In-Reply-To: <1589470709-4104-1-git-send-email-alexandru.elisei@arm.com>

A vesa device is used by the SDL, GTK or VNC framebuffers. Don't allow the
user to specify more than one of these options because kvmtool will create
identical vesa devices and bad things will happen:

$ ./lkvm run -c2 -m2048 -k bzImage --sdl --gtk
  # lkvm run -k bzImage -m 2048 -c 2 --name guest-10159
  Error: device region [d0000000-d012bfff] would overlap device region [d0000000-d012bfff]
*** Error in `./lkvm': free(): invalid pointer: 0x00007fad78002e40 ***
*** Error in `./lkvm': free(): invalid pointer: 0x00007fad78002e40 ***
*** Error in `./lkvm': free(): invalid pointer: 0x00007fad78002e40 ***
======= Backtrace: =========
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x777e5)[0x7fae0ed447e5]
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6/lib/x86_64-linux-gnu/libc.so.6(+0x8037a)[0x7fae0ed4d37a]
(+0x777e5)[0x7fae0ed447e5]
/lib/x86_64-linux-gnu/libc.so.6(+0x777e5)[0x7fae0ed447e5]
/lib/x86_64-linux-gnu/libc.so.6(+0x8037a)[0x7fae0ed4d37a]
/lib/x86_64-linux-gnu/libc.so.6(cfree+0x4c)[0x7fae0ed5153c]
*** Error in `./lkvm': free(): invalid pointer: 0x00007fad78002e40 ***
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_string_free+0x3b)[0x7fae0f814dab]
/lib/x86_64-linux-gnu/libglib-2.0.so.0(g_string_free+0x3b)[0x7fae0f814dab]
/usr/lib/x86_64-linux-gnu/libgtk-3.so.0(+0x21121c)[0x7fae1023321c]
/usr/lib/x86_64-linux-gnu/libgtk-3.so.0(+0x21121c)[0x7fae1023321c]
======= Backtrace: =========
Aborted (core dumped)

The vesa device is explicitly created during the initialization phase of
the above framebuffers. Also remove the superfluous check for their
existence.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 builtin-run.c | 5 +++++
 hw/vesa.c     | 2 --
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/builtin-run.c b/builtin-run.c
index 03b119e29995..c23e7a2e5ecd 100644
--- a/builtin-run.c
+++ b/builtin-run.c
@@ -543,6 +543,11 @@ static struct kvm *kvm_cmd_run_init(int argc, const char **argv)
 		kvm->cfg.console = DEFAULT_CONSOLE;
 
 	video = kvm->cfg.vnc || kvm->cfg.sdl || kvm->cfg.gtk;
+	if (video) {
+		if ((kvm->cfg.vnc && (kvm->cfg.sdl || kvm->cfg.gtk)) ||
+		    (kvm->cfg.sdl && kvm->cfg.gtk))
+			die("Only one of --vnc, --sdl or --gtk can be specified");
+	}
 
 	if (!strncmp(kvm->cfg.console, "virtio", 6))
 		kvm->cfg.active_console  = CONSOLE_VIRTIO;
diff --git a/hw/vesa.c b/hw/vesa.c
index dd59a112330b..a4ec7e16e1e6 100644
--- a/hw/vesa.c
+++ b/hw/vesa.c
@@ -61,8 +61,6 @@ struct framebuffer *vesa__init(struct kvm *kvm)
 	BUILD_BUG_ON(!is_power_of_two(VESA_MEM_SIZE));
 	BUILD_BUG_ON(VESA_MEM_SIZE < VESA_BPP/8 * VESA_WIDTH * VESA_HEIGHT);
 
-	if (!kvm->cfg.vnc && !kvm->cfg.sdl && !kvm->cfg.gtk)
-		return NULL;
 	vesa_base_addr = pci_get_io_port_block(PCI_IO_SIZE);
 	r = ioport__register(kvm, vesa_base_addr, &vesa_io_ops, PCI_IO_SIZE, NULL);
 	if (r < 0)
-- 
2.7.4

