From: David Matlack <dmatlack@google.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm list <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Kai Huang <kai.huang@intel.com>,
Michael Roth <michael.roth@amd.com>,
Tom Lendacky <thomas.lendacky@amd.com>
Subject: Re: [PATCH v2 2/3] KVM: x86/mmu: Fully re-evaluate MMIO caching when SPTE masks change
Date: Fri, 19 Aug 2022 09:21:42 -0700 [thread overview]
Message-ID: <CALzav=e_H0LU+2-KcG_bPahVhJM8YGnH24J6aJ9HG9Eqj-waew@mail.gmail.com> (raw)
In-Reply-To: <20220803224957.1285926-3-seanjc@google.com>
On Wed, Aug 3, 2022 at 3:50 PM Sean Christopherson <seanjc@google.com> wrote:
>
> Fully re-evaluate whether or not MMIO caching can be enabled when SPTE
> masks change; simply clearing enable_mmio_caching when a configuration
> isn't compatible with caching fails to handle the scenario where the
> masks are updated, e.g. by VMX for EPT or by SVM to account for the C-bit
> location, and toggle compatibility from false=>true.
>
> Snapshot the original module param so that re-evaluating MMIO caching
> preserves userspace's desire to allow caching. Use a snapshot approach
> so that enable_mmio_caching still reflects KVM's actual behavior.
Is updating module parameters to reflect the actual behavior (vs.
userspace desire) something we should do for all module parameters?
I am doing an unrelated refactor to the tdp_mmu module parameter and
noticed it is not updated e.g. if userspace loads kvm_intel with
ept=N.
next prev parent reply other threads:[~2022-08-19 17:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-03 22:49 [PATCH v2 0/3] KVM: x86/mmu: MMIO caching bug fixes Sean Christopherson
2022-08-03 22:49 ` [PATCH v2 1/3] KVM: x86: Tag kvm_mmu_x86_module_init() with __init Sean Christopherson
2022-08-03 22:49 ` [PATCH v2 2/3] KVM: x86/mmu: Fully re-evaluate MMIO caching when SPTE masks change Sean Christopherson
2022-08-03 22:59 ` Kai Huang
2022-08-04 0:16 ` Sean Christopherson
2022-08-19 16:21 ` David Matlack [this message]
2022-08-19 17:37 ` Paolo Bonzini
2022-08-24 21:08 ` Sean Christopherson
2022-08-03 22:49 ` [PATCH v2 3/3] KVM: SVM: Disable SEV-ES support if MMIO caching is disable Sean Christopherson
2022-08-05 11:17 ` [PATCH v2 0/3] KVM: x86/mmu: MMIO caching bug fixes Paolo Bonzini
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