From: Sean Christopherson <seanjc@google.com>
To: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Cc: kvm@vger.kernel.org, pbonzini@redhat.com, jmattson@google.com
Subject: Re: [PATCH 2/4 v2] KVM: nVMX: nSVM: 'nested_run' should count guest-entry attempts that make it to guest code
Date: Thu, 20 May 2021 14:53:11 +0000 [thread overview]
Message-ID: <YKZ3115oZOB7eH5d@google.com> (raw)
In-Reply-To: <20210520005012.68377-3-krish.sadhukhan@oracle.com>
On Wed, May 19, 2021, Krish Sadhukhan wrote:
> Currently, the 'nested_run' statistic counts all guest-entry attempts,
> including those that fail during vmentry checks on Intel and during
> consistency checks on AMD. Convert this statistic to count only those
> guest-entries that make it past these state checks and make it to guest
> code. This will tell us the number of guest-entries that actually executed
> or tried to execute guest code.
>
> Also, rename this statistic to 'nested_runs' since it is a count.
>
> Signed-off-by: Krish Sadhukhan <Krish.Sadhukhan@oracle.com>
> Suggested-by: Sean Christopherson <seanjc@google.com>
I didn't suggest this, or at least I didn't intend to. My point was that _if_
we want stat.nested_run to count successful VM-Enter then the counter should be
bumped only after VM-Enter succeeds. I did not mean to say that we should
actually do this. As Dongli pointed out[*], there is value in tracking attempts,
and I still don't understand _why_ we care about only counting successful
VM-Enters.
FWIW, this misses the case where L1 enters L2 in an inactive state.
[*] ed4a8dae-be99-0d88-a8dd-510afe7cb956@oracle.com
next prev parent reply other threads:[~2021-05-20 14:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 0:50 [PATCH 0/4 v2] KVM: nVMX: nSVM: Add more statistics to KVM debugfs Krish Sadhukhan
2021-05-20 0:50 ` [PATCH 1/4 v2] KVM: nVMX: Reset 'nested_run_pending' only in guest mode Krish Sadhukhan
2021-05-20 15:00 ` Sean Christopherson
2021-05-20 0:50 ` [PATCH 2/4 v2] KVM: nVMX: nSVM: 'nested_run' should count guest-entry attempts that make it to guest code Krish Sadhukhan
2021-05-20 14:53 ` Sean Christopherson [this message]
2021-05-20 17:58 ` Krish Sadhukhan
2021-05-20 0:50 ` [PATCH 3/4 v2] KVM: nVMX: nSVM: Add a new debugfs statistic to show how many VCPUs have run nested guests Krish Sadhukhan
2021-05-20 14:56 ` Sean Christopherson
2021-05-20 16:57 ` Jim Mattson
2021-05-20 18:01 ` Krish Sadhukhan
2021-05-20 0:50 ` [PATCH 4/4 v2] KVM: x86: Add a new VM statistic to show number of VCPUs created in a given VM Krish Sadhukhan
2021-05-20 15:04 ` Sean Christopherson
2021-05-21 18:06 ` Krish Sadhukhan
2021-05-27 17:46 ` Sean Christopherson
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