[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] SVM: limit GIF=0 region
>>> On 26.06.18 at 10:45, <andrew.cooper3@xxxxxxxxxx> wrote: > On 26/06/2018 08:32, Jan Beulich wrote: >> Use EFLAGS.IF for all ordinary purposes; there's in particular no need >> to unduly defer NMI/#MC. Clear/set GIF solely around VMRUN itself. This >> has the additional advantage that svm_stgi_label now indeed marks the >> only place where GIF is being set. >> >> A note regarding the main STI placement: Orignally I had it at the place >> the main STGI was sitting at so far. However, my Fam15 box reliably >> locks up hard with this, unless I have the NMI watchdog enabled. I can >> only deduce that the CPU doesn't like STGI with EFLAGS.IF clear plus >> some other condition (the lockup occurs only after exiting the boot >> loader in the guest). As there's nothing wrong with interrupts being on >> right after VMRUN, I've decided to put the STI right after the CLGI >> (matching what KVM does, i.e. having a fair chance of working >> everywhere). > > I'd like some input from AMD on this observation, because it is > completely bizarre. Would be nice indeed. >> @@ -96,13 +100,11 @@ __UNLIKELY_END(nsvm_hap) >> SPEC_CTRL_ENTRY_FROM_HVM /* Req: b=curr %rsp=regs/cpuinfo, Clob: >> acd */ >> /* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */ >> >> - STGI >> -GLOBAL(svm_stgi_label) > > Unfortunately, the stgi label must remain here. > SPEC_CTRL_ENTRY_FROM_HVM depends on NMIs being blocked to avoid > corrupting guest state. I'm afraid I don't follow: How are things safe then without NMIs blocked for VMX? Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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