Messages in this thread | | | Date | Mon, 4 Apr 2022 21:50:53 +0200 | From | "Maciej S. Szmigiero" <> | Subject | Re: [PATCH 5/8] KVM: SVM: Re-inject INT3/INTO instead of retrying the instruction |
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On 4.04.2022 21:33, Sean Christopherson wrote: > On Mon, Apr 04, 2022, Maciej S. Szmigiero wrote: >>>>> index 47e7427d0395..a770a1c7ddd2 100644 >>>>> --- a/arch/x86/kvm/svm/svm.h >>>>> +++ b/arch/x86/kvm/svm/svm.h >>>>> @@ -230,8 +230,8 @@ struct vcpu_svm { >>>>> bool nmi_singlestep; >>>>> u64 nmi_singlestep_guest_rflags; >>>>> - unsigned int3_injected; >>>>> - unsigned long int3_rip; >>>>> + unsigned soft_int_injected; >>>>> + unsigned long soft_int_linear_rip; >>>>> /* optional nested SVM features that are enabled for this guest */ >>>>> bool nrips_enabled : 1; >>>> >>>> >>>> I mostly agree with this patch, but think that it doesn't address the >>>> original issue that Maciej wanted to address: >>>> >>>> Suppose that there is *no* instruction in L2 code which caused the software >>>> exception, but rather L1 set arbitrary next_rip, and set EVENTINJ to software >>>> exception with some vector, and that injection got interrupted. >>>> >>>> I don't think that this code will support this. >>> >>> Argh, you're right. Maciej's selftest injects without an instruction, but it doesn't >>> configure the scenario where that injection fails due to an exception+VM-Exit that >>> isn't intercepted by L1 and is handled by L0. The event_inj test gets the coverage >>> for the latter, but always has a backing instruction. >> >> Still reviewing the whole patch set, but want to clear this point quickly: >> The selftest does have an implicit intervening NPF (handled by L0) while >> injecting the first L1 -> L2 event. > > I'll do some debug to figure out why the test passes for me. I'm guessing I either > got lucky, e.g. IDT was faulted in already, or I screwed up and the test doesn't > actually pass.
Try applying Maxim's proposed change to this test (adding two additional ud2s at the start of L2 guest code and adjusting just the next_rip field accordingly).
We might have been lucky in the patched KVM code and have next_rip = rip at this re-injection case now (the next_rip field was zero in the original KVM code).
Thanks, Maciej
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