Messages in this thread | | | Subject | Re: [PATCH -next] irq-chip/gic-v3-its: Fixed an issue where the ITS executes the residual commands in the queue again when the ITS wakes up from sleep mode. | From | "xuqiang (M)" <> | Date | Thu, 5 Nov 2020 22:06:34 +0800 |
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在 2020/11/5 21:12, Marc Zyngier 写道: > Please don't top-post. > > On 2020-11-05 11:54, xuqiang (M) wrote: >> The kernel sends three commands in the following sequence: >> >> 1.mapd(deviceA, ITT_addr1, valid:1) >> >> 2.mapti(deviceA):ITS write ITT_addr1 memory; >> >> 3.mapd(deviceA, ITT_addr1, valid:0) and kfree(ITT_addr1); >> >> 4.mapd(deviceA, ITT_addr2, valid:1); >> >> 5.mapti(deviceA):ITS write ITT_addr2 memory; >> >> In this case, the processor enters the sleep mode. After the kernel >> performs the suspend operation, the firmware performs the store >> operation and saves GITS_CBASER and GITS_CWRITER registers. >> >> Then, the processor is woken up, and the firmware restores GITS_CBASER >> and GITS_CWRITER registers. Because GITS_CWRITER register is not 0, >> ITS will read the above command sequence execution from the command >> queue, causing ITT_addr1 memory to be trampled. > > This cannot work. By doing a memset on the command queue, you are > only feeding crap to the ITS (command 0 simply does not exist). > Consider yourself lucky that it doesn't just lock-up. > > What needs to happen is the restore sequence that is already in the > driver, so that the command queue is in a sane state before re-enabling > the ITS. > > M.
On my platform, ITS_FLAGS_SAVE_SUSPEND_STATE is not set, thus
the first if condition in its_save_disable under list_for_each_entry goes
to the continue, however, I want to set the GITS_CWRITER to 0 at the
end of list_for_each_entry.
Do you have any suggestions about how to do this?
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