From: Peter Xu <peterx@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH 1/2] KVM: X86: Move ignore_msrs handling upper the stack
Date: Fri, 26 Jun 2020 13:37:50 -0400 [thread overview]
Message-ID: <20200626173750.GA175520@xz-x1> (raw)
In-Reply-To: <20200626155657.GC6583@linux.intel.com>
On Fri, Jun 26, 2020 at 08:56:57AM -0700, Sean Christopherson wrote:
> Not really? It's solving a problem that doesn't exist in the current code
> base (assuming TSC_CTRL is fixed), and IMO solving it in an ugly fashion.
>
> I would much prefer that, _if_ we want to support blind KVM-internal MSR
> accesses, we end up with code like:
>
> if (msr_info->kvm_internal) {
> return 1;
> } else if (!ignore_msrs) {
> vcpu_debug_ratelimited(vcpu, "unhandled wrmsr: 0x%x data 0x%llx\n",
> msr, data);
> return 1;
> } else {
> if (report_ignored_msrs)
> vcpu_unimpl(vcpu,
> "ignored wrmsr: 0x%x data 0x%llx\n",
> msr, data);
> break;
> }
>
> But I'm still not convinced that there is a legimiate scenario for setting
> kvm_internal=true.
Actually this really looks like my initial version when I was discussing this
with Paolo before this version, but Paolo suggested what I implemented last. I
think I agree with Paolo that it's an improvement to have a way to get/set real
msr value so that we don't need to further think about effects being taken with
the two tricky msr knobs (report_ignored_msrs, ignore_msrs). These knobs are
even trickier to me when they're hidden deep, because they are not easily
expected when seeing the name of the functions (e.g. __kvm_set_msr, rather than
__kvm_set_msr_retval_fixed).
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2020-06-26 17:37 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-22 22:04 [PATCH 0/2] KVM: X86: A few fixes around ignore_msrs Peter Xu
2020-06-22 22:04 ` [PATCH 1/2] KVM: X86: Move ignore_msrs handling upper the stack Peter Xu
2020-06-25 6:15 ` Sean Christopherson
2020-06-25 8:09 ` Paolo Bonzini
2020-06-25 16:25 ` Sean Christopherson
2020-06-25 17:45 ` Sean Christopherson
2020-06-25 18:44 ` Paolo Bonzini
2020-06-26 15:56 ` Sean Christopherson
2020-06-26 17:37 ` Peter Xu [this message]
2020-06-26 17:46 ` Sean Christopherson
2020-06-26 18:07 ` Peter Xu
2020-06-26 18:18 ` Sean Christopherson
2020-06-26 19:11 ` Peter Xu
2020-06-27 14:24 ` Paolo Bonzini
2020-06-30 15:47 ` Sean Christopherson
2020-07-09 18:22 ` Peter Xu
2020-07-09 18:24 ` Paolo Bonzini
2020-07-09 18:34 ` Peter Xu
2020-07-09 19:24 ` Sean Christopherson
2020-07-09 21:09 ` Peter Xu
2020-07-09 21:26 ` Sean Christopherson
2020-07-09 21:50 ` Peter Xu
2020-07-09 22:11 ` Paolo Bonzini
2020-07-10 4:58 ` Sean Christopherson
2020-06-22 22:04 ` [PATCH 2/2] KVM: X86: Do the same ignore_msrs check for feature msrs Peter Xu
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