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2024-04-25reset: Add RESET_TYPE_SNAPSHOT_LOADPeter Maydell
Some devices and machines need to handle the reset before a vmsave snapshot is loaded differently -- the main user is the handling of RNG seed information, which does not want to put a new RNG seed into a ROM blob when we are doing a snapshot load. Currently this kind of reset handling is supported only for: * TYPE_MACHINE reset methods, which take a ShutdownCause argument * reset functions registered with qemu_register_reset_nosnapshotload To allow a three-phase-reset device to also distinguish "snapshot load" reset from the normal kind, add a new ResetType RESET_TYPE_SNAPSHOT_LOAD. All our existing reset methods ignore the reset type, so we don't need to update any device code. Add the enum type, and make qemu_devices_reset() use the right reset type for the ShutdownCause it is passed. This allows us to get rid of the device_reset_reason global we were using to implement qemu_register_reset_nosnapshotload(). Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Reviewed-by: Luc Michel <luc.michel@amd.com> Message-id: 20240412160809.1260625-7-peter.maydell@linaro.org
2024-04-25hw, target: Add ResetType argument to hold and exit phase methodsPeter Maydell
We pass a ResetType argument to the Resettable class enter phase method, but we don't pass it to hold and exit, even though the callsites have it readily available. This means that if a device cared about the ResetType it would need to record it in the enter phase method to use later on. Pass the type to all three of the phase methods to avoid having to do that. Commit created with for dir in hw target include; do \ spatch --macro-file scripts/cocci-macro-file.h \ --sp-file scripts/coccinelle/reset-type.cocci \ --keep-comments --smpl-spacing --in-place \ --include-headers --dir $dir; done and no manual edits. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Edgar E. Iglesias <edgar.iglesias@amd.com> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Luc Michel <luc.michel@amd.com> Message-id: 20240412160809.1260625-5-peter.maydell@linaro.org
2022-10-27hw/core/resettable: fix reset level countingDamien Hedde
The code for handling the reset level count in the Resettable code has two issues: The reset count is only decremented for the 1->0 case. This means that if there's ever a nested reset that takes the count to 2 then it will never again be decremented. Eventually the count will exceed the '50' limit in resettable_phase_enter() and QEMU will trip over the assertion failure. The repro case in issue 1266 is an example of this that happens now the SCSI subsystem uses three-phase reset. Secondly, the count is decremented only after the exit phase handler is called. Moving the reset count decrement from "just after" to "just before" calling the exit phase handler allows resettable_is_in_reset() to return false during the handler execution. This simplifies reset handling in resettable devices. Typically, a function that updates the device state will just need to read the current reset state and not anymore treat the "in a reset-exit transition" as a special case. Note that the semantics change to the *_is_in_reset() functions will have no effect on the current codebase, because only two devices (hw/char/cadence_uart.c and hw/misc/zynq_sclr.c) currently call those functions, and in neither case do they do it from the device's exit phase methed. Fixes: 4a5fc890 ("scsi: Use device_cold_reset() and bus_cold_reset()") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1266 Signed-off-by: Damien Hedde <damien.hedde@greensocs.com> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reported-by: Michael Peter <michael.peter@hensoldt-cyber.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Message-id: 20221020142749.3357951-1-peter.maydell@linaro.org Buglink: https://bugs.launchpad.net/qemu/+bug/1905297 Reported-by: Michael Peter <michael.peter@hensoldt-cyber.com> [PMM: adjust the docs paragraph changed to get the name of the 'enter' phase right and to clarify exactly when the count is adjusted; rewrite the commit message] Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2020-01-30hw/core: deprecate old reset functions and introduce new onesDamien Hedde
Deprecate device_legacy_reset(), qdev_reset_all() and qbus_reset_all() to be replaced by new functions device_cold_reset() and bus_cold_reset() which uses resettable API. Also introduce resettable_cold_reset_fn() which may be used as a replacement for qdev_reset_all_fn and qbus_reset_all_fn(). Following patches will be needed to look at legacy reset call sites and switch to resettable api. The legacy functions will be removed when unused. Signed-off-by: Damien Hedde <damien.hedde@greensocs.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-id: 20200123132823.1117486-9-damien.hedde@greensocs.com Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2020-01-30hw/core/resettable: add support for changing parentDamien Hedde
Add a function resettable_change_parent() to do the required plumbing when changing the parent a of Resettable object. We need to make sure that the reset state of the object remains coherent with the reset state of the new parent. We make the 2 following hypothesis: + when an object is put in a parent under reset, the object goes in reset. + when an object is removed from a parent under reset, the object leaves reset. The added function avoids any glitch if both old and new parent are already in reset. Signed-off-by: Damien Hedde <damien.hedde@greensocs.com> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-id: 20200123132823.1117486-6-damien.hedde@greensocs.com Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2020-01-30hw/core: create Resettable QOM interfaceDamien Hedde
This commit defines an interface allowing multi-phase reset. This aims to solve a problem of the actual single-phase reset (built in DeviceClass and BusClass): reset behavior is dependent on the order in which reset handlers are called. In particular doing external side-effect (like setting an qemu_irq) is problematic because receiving object may not be reset yet. The Resettable interface divides the reset in 3 well defined phases. To reset an object tree, all 1st phases are executed then all 2nd then all 3rd. See the comments in include/hw/resettable.h for a more complete description. The interface defines 3 phases to let the future possibility of holding an object into reset for some time. The qdev/qbus reset in DeviceClass and BusClass will be modified in following commits to use this interface. A mechanism is provided to allow executing a transitional reset handler in place of the 2nd phase which is executed in children-then-parent order inside a tree. This will allow to transition devices and buses smoothly while keeping the exact current qdev/qbus reset behavior for now. Documentation will be added in a following commit. Signed-off-by: Damien Hedde <damien.hedde@greensocs.com> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-id: 20200123132823.1117486-4-damien.hedde@greensocs.com Signed-off-by: Peter Maydell <peter.maydell@linaro.org>