hw/sd: sdhci: Don't write to SDHC_SYSAD register when transfer is in progress

hw/sd: sdhci: Don't write to SDHC_SYSAD register when transfer is in progress

Per "SD Host Controller Standard Specification Version 7.00"
chapter 2.2.1 SDMA System Address Register:

This register can be accessed only if no transaction is executing
(i.e., after a transaction has stopped).

With this fix, the following reproducer:

outl 0xcf8 0x80001010
outl 0xcfc 0xfbefff00
outl 0xcf8 0x80001001
outl 0xcfc 0x06000000
write 0xfbefff2c 0x1 0x05
write 0xfbefff0f 0x1 0x37
write 0xfbefff0a 0x1 0x01
write 0xfbefff0f 0x1 0x29
write 0xfbefff0f 0x1 0x02
write 0xfbefff0f 0x1 0x03
write 0xfbefff04 0x1 0x01
write 0xfbefff05 0x1 0x01
write 0xfbefff07 0x1 0x02
write 0xfbefff0c 0x1 0x33
write 0xfbefff0e 0x1 0x20
write 0xfbefff0f 0x1 0x00
write 0xfbefff2a 0x1 0x01
write 0xfbefff0c 0x1 0x00
write 0xfbefff03 0x1 0x00
write 0xfbefff05 0x1 0x00
write 0xfbefff2a 0x1 0x02
write 0xfbefff0c 0x1 0x32
write 0xfbefff01 0x1 0x01
write 0xfbefff02 0x1 0x01
write 0xfbefff03 0x1 0x01

cannot be reproduced with the following QEMU command line:

$ qemu-system-x86_64 -nographic -machine accel=qtest -m 512M \
       -nodefaults -device sdhci-pci,sd-spec-version=3 \
       -drive if=sd,index=0,file=null-co://,format=raw,id=mydrive \
       -device sd-card,drive=mydrive -qtest stdio

Cc: qemu-stable@nongnu.org
Fixes: CVE-2020-17380
Fixes: CVE-2020-25085
Fixes: CVE-2021-3409
Fixes: d7dfca0807a0 ("hw/sdhci: introduce standard SD host controller")
Reported-by: Alexander Bulekov <alxndr@bu.edu>
Reported-by: Cornelius Aschermann (Ruhr-Universität Bochum)
Reported-by: Sergej Schumilo (Ruhr-Universität Bochum)
Reported-by: Simon Wörner (Ruhr-Universität Bochum)
Buglink: https://bugs.launchpad.net/qemu/+bug/1892960
Buglink: https://bugs.launchpad.net/qemu/+bug/1909418
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1928146
Tested-by: Alexander Bulekov <alxndr@bu.edu>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Message-Id: <20210303122639.20004-3-bmeng.cn@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>