From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Sean Christopherson <seanjc@google.com>,
Jim Mattson <jmattson@google.com>
Cc: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Anirudh Rayabharam <anrayabh@linux.microsoft.com>,
Wanpeng Li <wanpengli@tencent.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 22/28] KVM: VMX: Clear controls obsoleted by EPT at runtime, not setup
Date: Fri, 08 Jul 2022 09:55:45 +0200 [thread overview]
Message-ID: <87tu7sox6m.fsf@redhat.com> (raw)
In-Reply-To: <YsdSfP7xmMcLv8i9@google.com>
Sean Christopherson <seanjc@google.com> writes:
> On Thu, Jul 07, 2022, Jim Mattson wrote:
>> On Thu, Jul 7, 2022 at 12:30 PM Sean Christopherson <seanjc@google.com> wrote:
>> >
>> > On Thu, Jul 07, 2022, Vitaly Kuznetsov wrote:
>> > > Jim Mattson <jmattson@google.com> writes:
>> > >
>> > > > On Wed, Jun 29, 2022 at 8:07 AM Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
>> > > >>
>> > > >> From: Sean Christopherson <seanjc@google.com>
>> > > >>
>> > > >> Clear the CR3 and INVLPG interception controls at runtime based on
>> > > >> whether or not EPT is being _used_, as opposed to clearing the bits at
>> > > >> setup if EPT is _supported_ in hardware, and then restoring them when EPT
>> > > >> is not used. Not mucking with the base config will allow using the base
>> > > >> config as the starting point for emulating the VMX capability MSRs.
>> > > >>
>> > > >> Signed-off-by: Sean Christopherson <seanjc@google.com>
>> > > >> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>> > > > Nit: These controls aren't "obsoleted" by EPT; they're just no longer
>> > > > required.
>
> Actually, they're still required if unrestricted guest isn't supported.
>
>> > Isn't that the definition of "obsolete"? They're "no longer in use" when KVM
>> > enables EPT.
>>
>> There are still reasons to use them aside from shadow page table
>> maintenance. For example, malware analysis may be interested in
>> intercepting CR3 changes to track process context (and to
>> enable/disable costly monitoring). EPT doesn't render these events
>> "obsolete," because you can't intercept these events using EPT.
>
> Fair enough, I was using "EPT" in the "KVM is using EPT" sense. But even that's
> wrong as KVM intercepts CR3 accesses when EPT is enabled, but unrestricted guest
> is disabled and the guest disables paging.
>
> Vitaly, since the CR3 fields are still technically "needed", maybe just be
> explicit?
>
> KVM: VMX: Adjust CR3/INVPLG interception for EPT=y at runtime, not setup
>
Sounds good, adjusted!
--
Vitaly
next prev parent reply other threads:[~2022-07-08 7:55 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-29 15:05 [PATCH v2 00/28] KVM: VMX: Support TscScaling and EnclsExitingBitmap with eVMCS + use vmcs_config for L1 VMX MSRs Vitaly Kuznetsov
2022-06-29 15:05 ` [PATCH v2 01/28] KVM: x86: hyper-v: Expose access to debug MSRs in the partition privilege flags Vitaly Kuznetsov
2022-06-29 15:05 ` [PATCH v2 02/28] x86/hyperv: Fix 'struct hv_enlightened_vmcs' definition Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 03/28] x86/hyperv: Update " Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 04/28] KVM: VMX: Define VMCS-to-EVMCS conversion for the new fields Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 05/28] KVM: nVMX: Support several new fields in eVMCSv1 Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 06/28] KVM: nVMX: Introduce KVM_CAP_HYPERV_ENLIGHTENED_VMCS2 Vitaly Kuznetsov
2022-07-06 21:35 ` Sean Christopherson
2022-07-07 9:58 ` Vitaly Kuznetsov
2022-07-07 16:17 ` Sean Christopherson
2022-07-07 16:40 ` Sean Christopherson
2022-06-29 15:06 ` [PATCH v2 07/28] KVM: selftests: Switch to KVM_CAP_HYPERV_ENLIGHTENED_VMCS2 Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 08/28] KVM: VMX: Support TSC scaling with enlightened VMCS Vitaly Kuznetsov
2022-07-07 10:01 ` Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 09/28] KVM: selftests: Add ENCLS_EXITING_BITMAP{,HIGH} VMCS fields Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 10/28] KVM: selftests: Switch to updated eVMCSv1 definition Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 11/28] KVM: selftests: Enable TSC scaling in evmcs selftest Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 12/28] KVM: VMX: Enable VM_{EXIT,ENTRY}_LOAD_IA32_PERF_GLOBAL_CTRL for KVM on Hyper-V Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 13/28] KVM: VMX: Get rid of eVMCS specific VMX controls sanitization Vitaly Kuznetsov
2022-07-06 22:27 ` Sean Christopherson
2022-07-07 10:03 ` Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 14/28] KVM: VMX: Check VM_ENTRY_IA32E_MODE in setup_vmcs_config() Vitaly Kuznetsov
2022-06-29 20:28 ` Jim Mattson
2022-06-29 15:06 ` [PATCH v2 15/28] KVM: VMX: Check CPU_BASED_{INTR,NMI}_WINDOW_EXITING " Vitaly Kuznetsov
2022-07-01 3:58 ` Jim Mattson
2022-07-01 8:12 ` Vitaly Kuznetsov
2022-07-06 18:44 ` Sean Christopherson
2022-06-29 15:06 ` [PATCH v2 16/28] KVM: VMX: Tweak the special handling of SECONDARY_EXEC_ENCLS_EXITING " Vitaly Kuznetsov
2022-06-29 18:56 ` Jim Mattson
2022-06-30 7:32 ` Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 17/28] KVM: VMX: Extend VMX controls macro shenanigans Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 18/28] KVM: VMX: Move CPU_BASED_CR8_{LOAD,STORE}_EXITING filtering out of setup_vmcs_config() Vitaly Kuznetsov
2022-07-01 4:14 ` Jim Mattson
2022-06-29 15:06 ` [PATCH v2 19/28] KVM: VMX: Add missing VMEXIT controls to vmcs_config Vitaly Kuznetsov
2022-07-01 16:02 ` Jim Mattson
2022-06-29 15:06 ` [PATCH v2 20/28] KVM: VMX: Add missing VMENTRY " Vitaly Kuznetsov
2022-07-01 16:01 ` Jim Mattson
2022-07-07 10:41 ` Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 21/28] KVM: VMX: Add missing CPU based VM execution " Vitaly Kuznetsov
2022-07-01 16:05 ` Jim Mattson
2022-06-29 15:06 ` [PATCH v2 22/28] KVM: VMX: Clear controls obsoleted by EPT at runtime, not setup Vitaly Kuznetsov
2022-07-01 16:11 ` Jim Mattson
2022-07-07 14:57 ` Vitaly Kuznetsov
2022-07-07 19:30 ` Sean Christopherson
2022-07-07 21:32 ` Jim Mattson
2022-07-07 21:39 ` Sean Christopherson
2022-07-07 23:12 ` Jim Mattson
2022-07-08 7:55 ` Vitaly Kuznetsov [this message]
2022-06-29 15:06 ` [PATCH v2 23/28] KVM: VMX: Move LOAD_IA32_PERF_GLOBAL_CTRL errata handling out of setup_vmcs_config() Vitaly Kuznetsov
2022-07-01 16:26 ` Jim Mattson
2022-07-07 12:07 ` Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 24/28] KVM: nVMX: Use sanitized allowed-1 bits for VMX control MSRs Vitaly Kuznetsov
2022-07-01 22:54 ` Jim Mattson
2022-07-07 12:30 ` Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 25/28] KVM: VMX: Store required-1 VMX controls in vmcs_config Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 26/28] KVM: nVMX: Use sanitized required-1 bits for VMX control MSRs Vitaly Kuznetsov
2022-06-29 15:06 ` [PATCH v2 27/28] KVM: VMX: Cache MSR_IA32_VMX_MISC in vmcs_config Vitaly Kuznetsov
2022-06-29 18:33 ` Jim Mattson
2022-06-29 15:06 ` [PATCH v2 28/28] KVM: nVMX: Use cached host MSR_IA32_VMX_MISC value for setting up nested MSR Vitaly Kuznetsov
2022-06-29 18:37 ` Jim Mattson
2022-06-30 7:36 ` Vitaly Kuznetsov
2022-06-30 12:27 ` Jim Mattson
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