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Re: [Qemu-devel] [PATCH v1 1/1] RISC-V: Workaround for critical mstatus.
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH v1 1/1] RISC-V: Workaround for critical mstatus.FS MTTCG bug |
Date: |
Wed, 28 Mar 2018 10:26:30 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 |
On 03/28/2018 08:15 AM, Michael Clark wrote:
> On looking at this again, I think we may need to remove
> the qemu_tcg_mttcg_enabled conditional and always return dirty if the state is
> initial or clean, but not off.
Yes.
> While testing on uniprocessor worked okay, it's likely because we were lucky
> and there was no task migration or multiple FPU tasks working.
Also yes.
> > + if (qemu_tcg_mttcg_enabled()) {
> > + /* FP is always dirty or off */
> > + if (mstatus & MSTATUS_FS) {
> > + mstatus |= MSTATUS_FS;
> > + }
> > + }
I've just posted an alternate patch set to track MSTATUS_FS more exactly, but
if that's thought to be too much this late in the cycle, then I'll sign off on
this patch without the mttcg test.
r~