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FEAT_WFxT introduces new instructions WFIT and WFET, which are like
the existing WFI and WFE but allow the guest to pass a timeout value
in a register. The instructions will wait for an interrupt/event as
usual, but will also stop waiting when the value of CNTVCT_EL0 is
greater than or equal to the specified timeout value.
We implement WFIT by setting up a timer to expire at the right
point; when the timer expires it sets the EXITTB interrupt, which
will cause the CPU to leave the halted state. If we come out of
halt for some other reason, we unset the pending timer.
We implement WFET as a nop, which is architecturally permitted and
matches the way we currently make WFE a nop.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240430140035.3889879-3-peter.maydell@linaro.org
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Architecturally, the AArch32 MSR/MRS to/from banked register
instructions are UNPREDICTABLE for attempts to access a banked
register that the guest could access in a more direct way (e.g.
using this insn to access r8_fiq when already in FIQ mode). QEMU has
chosen to UNDEF on all of these.
However, for the case of accessing SPSR_hyp from hyp mode, it turns
out that real hardware permits this, with the same effect as if the
guest had directly written to SPSR. Further, there is some
guest code out there that assumes it can do this, because it
happens to work on hardware: an example Cortex-R52 startup code
fragment uses this, and it got copied into various other places,
including Zephyr. Zephyr was fixed to not use this:
https://github.com/zephyrproject-rtos/zephyr/issues/47330
but other examples are still out there, like the selftest
binary for the MPS3-AN536.
For convenience of being able to run guest code, permit
this UNPREDICTABLE access instead of UNDEFing it.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240206132931.38376-5-peter.maydell@linaro.org
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The HCR_EL2.TSC trap for trapping EL1 execution of SMC instructions
has a behaviour change for FEAT_NV when EL3 is not implemented:
* in older architecture versions TSC was required to have no
effect (i.e. the SMC insn UNDEFs)
* with FEAT_NV, when HCR_EL2.NV == 1 the trap must apply
(i.e. SMC traps to EL2, as it already does in all cases when
EL3 is implemented)
* in newer architecture versions, the behaviour either without
FEAT_NV or with FEAT_NV and HCR_EL2.NV == 0 is relaxed to
an IMPDEF choice between UNDEF and trap-to-EL2 (i.e. it is
permitted to always honour HCR_EL2.TSC) for AArch64 only
Add the condition to honour the trap bit when HCR_EL2.NV == 1. We
leave the HCR_EL2.NV == 0 case with the existing (UNDEF) behaviour,
as our IMPDEF choice (both because it avoids a behaviour change
for older CPU models and because we'd have to distinguish AArch32
from AArch64 if we opted to trap to EL2).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Miguel Luis <miguel.luis@oracle.com>
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The Big QEMU Lock (BQL) has many names and they are confusing. The
actual QemuMutex variable is called qemu_global_mutex but it's commonly
referred to as the BQL in discussions and some code comments. The
locking APIs, however, are called qemu_mutex_lock_iothread() and
qemu_mutex_unlock_iothread().
The "iothread" name is historic and comes from when the main thread was
split into into KVM vcpu threads and the "iothread" (now called the main
loop thread). I have contributed to the confusion myself by introducing
a separate --object iothread, a separate concept unrelated to the BQL.
The "iothread" name is no longer appropriate for the BQL. Rename the
locking APIs to:
- void bql_lock(void)
- void bql_unlock(void)
- bool bql_locked(void)
There are more APIs with "iothread" in their names. Subsequent patches
will rename them. There are also comments and documentation that will be
updated in later patches.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Fabiano Rosas <farosas@suse.de>
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Acked-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20240102153529.486531-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20231130142519.28417-2-philmd@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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The feature test functions isar_feature_*() now take up nearly
a thousand lines in target/arm/cpu.h. This header file is included
by a lot of source files, most of which don't need these functions.
Move the feature test functions to their own header file.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20231024163510.2972081-2-peter.maydell@linaro.org
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Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230831232441.66020-5-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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Perform the check for EL2 enabled in the security space and the
TIDCP bit in an out-of-line helper.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230831232441.66020-4-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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Signed-off-by: Claudio Fontana <cfontana@suse.de>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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