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Date:   Thu, 20 Jan 2022 18:29:25 +0100
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Subject: Re: [PATCH v2 4/7] kvm/mips: rework guest entry logic
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To:     Mark Rutland <mark.rutland@arm.com>
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References: <20220119105854.3160683-1-mark.rutland@arm.com>
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 <20220120164455.GA15464@C02TD0UTHF1T.local>
 <a2b628b4-907c-4e15-df91-18c0db099228@redhat.com>
 <20220120171551.GB15464@C02TD0UTHF1T.local>
From:   Paolo Bonzini <pbonzini@redhat.com>
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On 1/20/22 18:15, Mark Rutland wrote:
> As above, we'll also need the guest_state_{enter,exit}() calls
> surrounding this (e.g. before that local_irq_enable() at the start of
> kvm_mips_handle_exit(),

Oh, indeed.  And there is also an interrupt-enabled area similar to 
s390's, in both vcpu_run and the exception handler entry point (which 
falls through to the exit handler created by kvm_mips_build_exit).  For 
example:

         /* Setup status register for running guest in UM */
         uasm_i_ori(&p, V1, V1, ST0_EXL | KSU_USER | ST0_IE);
         UASM_i_LA(&p, AT, ~(ST0_CU0 | ST0_MX | ST0_SX | ST0_UX));
         uasm_i_and(&p, V1, V1, AT);
         uasm_i_mtc0(&p, V1, C0_STATUS);
         uasm_i_ehb(&p);

I'd rather get rid altogether of the EQS for MIPS.

> and that needs to happen in noinstr code, etc.

There are bigger problems with instrumentation, because the 
runtime-generated code as far as I can tell is not noinstr.

Paolo