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author | James Morse <james.morse@arm.com> | 2018-05-04 16:19:24 +0100 |
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committer | Marc Zyngier <marc.zyngier@arm.com> | 2018-05-04 16:45:55 +0100 |
commit | b220244d41798c6592e7d17843256eb0bae456a0 (patch) | |
tree | 14da5fbe2ea41056a8dd2fe84adf67925199a06a /arch/nds32/mm | |
parent | c3616a077190435cb540e134d5dfcd15207817ee (diff) | |
download | linux-b220244d41798c6592e7d17843256eb0bae456a0.tar.bz2 |
arm64: vgic-v2: Fix proxying of cpuif access
Proxying the cpuif accesses at EL2 makes use of vcpu_data_guest_to_host
and co, which check the endianness, which call into vcpu_read_sys_reg...
which isn't mapped at EL2 (it was inlined before, and got moved OoL
with the VHE optimizations).
The result is of course a nice panic. Let's add some specialized
cruft to keep the broken platforms that require this hack alive.
But, this code used vcpu_data_guest_to_host(), which expected us to
write the value to host memory, instead we have trapped the guest's
read or write to an mmio-device, and are about to replay it using the
host's readl()/writel() which also perform swabbing based on the host
endianness. This goes wrong when both host and guest are big-endian,
as readl()/writel() will undo the guest's swabbing, causing the
big-endian value to be written to device-memory.
What needs doing?
A big-endian guest will have pre-swabbed data before storing, undo this.
If its necessary for the host, writel() will re-swab it.
For a read a big-endian guest expects to swab the data after the load.
The hosts's readl() will correct for host endianness, giving us the
device-memory's value in the register. For a big-endian guest, swab it
as if we'd only done the load.
For a little-endian guest, nothing needs doing as readl()/writel() leave
the correct device-memory value in registers.
Tested on Juno with that rarest of things: a big-endian 64K host.
Based on a patch from Marc Zyngier.
Reported-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Fixes: bf8feb39642b ("arm64: KVM: vgic-v2: Add GICV access from HYP")
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'arch/nds32/mm')
0 files changed, 0 insertions, 0 deletions