From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: qemu-devel@nongnu.org
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
"Michael S . Tsirkin" <mst@redhat.com>,
"Michael Tokarev" <mjt@tls.msk.ru>,
"Philippe Mathieu-Daudé" <f4bug@amsat.org>,
"Paolo Bonzini" <pbonzini@redhat.com>
Subject: [RFC PATCH-not-for-5.1? v2] hw/isa/isa-bus: Ensure ISA I/O regions are 8/16-bit accessible
Date: Mon, 20 Jul 2020 20:57:58 +0200 [thread overview]
Message-ID: <20200720185758.21280-1-f4bug@amsat.org> (raw)
Since commit 5d971f9e67 we don't accept mismatching sizes
in memory_region_access_valid(). This gives troubles when
a device is on an ISA bus, because the CPU is free to use
8/16-bit accesses on the bus (or up to 32-bit on EISA bus),
regardless what range is valid for the device.
Add a check to ensure devices plugged on the ISA bus can
accept 8/16-bits accesses.
Related bug reports:
- https://lore.kernel.org/xen-devel/20200630170913.123646-1-anthony.perard@citrix.com/T/
- https://bugs.debian.org/964793
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=964247
- https://bugs.launchpad.net/bugs/1886318
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
MST: I really don't like this approach, I think the ISA bus
should adjust the access.
since v1: only 8/16-bit accesses enforced
---
hw/isa/isa-bus.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/hw/isa/isa-bus.c b/hw/isa/isa-bus.c
index 58fde178f9..e142eeef06 100644
--- a/hw/isa/isa-bus.c
+++ b/hw/isa/isa-bus.c
@@ -132,6 +132,20 @@ static inline void isa_init_ioport(ISADevice *dev, uint16_t ioport)
void isa_register_ioport(ISADevice *dev, MemoryRegion *io, uint16_t start)
{
+ if (io->ops->valid.min_access_size > 1) {
+ /*
+ * To be backward compatible with IBM-PC bus, ISA bus must accept
+ * 8-bit accesses.
+ */
+ error_report("ISA device '%s' requires I/O min_access_size of 1 (byte)",
+ object_get_typename(OBJECT(dev)));
+ exit(1);
+ } else if (io->ops->valid.max_access_size < 2) {
+ /* ISA bus must accept 16-bit accesses (EISA accepts 32-bit) */
+ error_report("ISA device '%s' requires I/O max_access_size of "
+ "at least 2 (bytes)", object_get_typename(OBJECT(dev)));
+ exit(1);
+ }
memory_region_add_subregion(isabus->address_space_io, start, io);
isa_init_ioport(dev, start);
}
--
2.21.3
next reply other threads:[~2020-07-20 18:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-20 18:57 Philippe Mathieu-Daudé [this message]
2020-07-20 19:45 ` [RFC PATCH-not-for-5.1? v2] hw/isa/isa-bus: Ensure ISA I/O regions are 8/16-bit accessible Michael Tokarev
2020-07-21 12:29 ` Philippe Mathieu-Daudé
2020-07-22 6:43 ` Michael Tokarev
2020-07-22 11:17 ` Michael S. Tsirkin
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