From: Paolo Bonzini <firstname.lastname@example.org> To: Sean Christopherson <email@example.com> Cc: Vitaly Kuznetsov <firstname.lastname@example.org>, Wanpeng Li <email@example.com>, Jim Mattson <firstname.lastname@example.org>, Joerg Roedel <email@example.com>, firstname.lastname@example.org, email@example.com, Xiaoyao Li <firstname.lastname@example.org>, Reiji Watanabe <email@example.com> Subject: Re: [PATCH 11/15] KVM: VMX: Disable loading of TSX_CTRL MSR the more conventional way Date: Wed, 5 May 2021 17:50:35 +0200 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <YJK7jzbihzFIkb59@google.com> On 05/05/21 17:36, Sean Christopherson wrote: > On Wed, May 05, 2021, Paolo Bonzini wrote: >> On 04/05/21 19:17, Sean Christopherson wrote: >>> Tag TSX_CTRL as not needing to be loaded when RTM isn't supported in the >>> host. Crushing the write mask to '0' has the same effect, but requires >>> more mental gymnastics to understand. >> >> This doesn't explain _why_ this is now possible. What about: >> >> Now that user return MSRs is always present in the list, we don't have > > User return MSRs aren't always present in the list; this series doesn't change > that behavior at all. > >> the problem that the TSX_CTRL MSR needs a slot vmx->guest_uret_msrs even >> if RTM is not supported in the host (and therefore there is nothing to >> enable). Thus we can simply tag TSX_CTRL as not needing to be loaded >> instead of crushing the write mask to '0'. > > Unless I'm missing something, it would have been possible to give TSX_CTRL a > slot but not load it even before this refactoring, we just missed that approach > when handling the TSX_CTRL without HLE/RTM case. Several other MSRs rely on > this behavior, notably the SYSCALL MSRs, which are present in the list so that > the guest can read/write the MSRs, but are loaded into hardware iff the guest > has enabled SYSCALL. You're right, it used to be done with vmx->nr_active_uret_msr. Paolo > All that said, I certainly have no objection to writing a longer changelog.
next prev parent reply other threads:[~2021-05-05 15:50 UTC|newest] Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-04 17:17 [PATCH 00/15] KVM: x86: RDPID/RDTSCP fixes and uret MSR cleanups Sean Christopherson 2021-05-04 17:17 ` [PATCH 01/15] KVM: VMX: Do not adverise RDPID if ENABLE_RDTSCP control is unsupported Sean Christopherson 2021-05-04 17:37 ` Jim Mattson 2021-05-04 17:53 ` Jim Mattson 2021-05-04 18:14 ` Sean Christopherson 2021-05-05 3:04 ` Reiji Watanabe 2021-05-10 8:03 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 02/15] KVM: x86: Emulate RDPID only if RDTSCP is supported Sean Christopherson 2021-05-04 17:50 ` Jim Mattson 2021-05-05 3:51 ` Reiji Watanabe 2021-05-05 8:01 ` Paolo Bonzini 2021-05-10 8:08 ` Maxim Levitsky 2021-05-10 17:20 ` Sean Christopherson 2021-05-11 12:32 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 03/15] KVM: SVM: Inject #UD on RDTSCP when it should be disabled in the guest Sean Christopherson 2021-05-04 21:45 ` Jim Mattson 2021-05-04 21:53 ` Sean Christopherson 2021-05-04 21:56 ` Jim Mattson 2021-05-04 22:10 ` Sean Christopherson 2021-05-04 22:24 ` Jim Mattson 2021-05-04 21:57 ` Paolo Bonzini 2021-05-04 21:58 ` Jim Mattson 2021-05-10 8:08 ` Maxim Levitsky 2021-05-10 16:56 ` Sean Christopherson 2021-05-11 12:34 ` Maxim Levitsky 2021-05-18 10:59 ` Paolo Bonzini 2021-05-18 19:24 ` Sean Christopherson 2021-05-05 4:26 ` Reiji Watanabe 2021-05-10 8:08 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 04/15] KVM: x86: Move RDPID emulation intercept to its own enum Sean Christopherson 2021-05-04 23:24 ` Jim Mattson 2021-05-10 8:14 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 05/15] KVM: VMX: Disable preemption when probing user return MSRs Sean Christopherson 2021-05-04 23:36 ` Jim Mattson 2021-05-10 8:18 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 06/15] KVM: SVM: Probe and load MSR_TSC_AUX regardless of RDTSCP support in host Sean Christopherson 2021-05-10 8:20 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 07/15] KVM: x86: Add support for RDPID without RDTSCP Sean Christopherson 2021-05-10 8:20 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 08/15] KVM: VMX: Configure list of user return MSRs at module init Sean Christopherson 2021-05-10 8:23 ` Maxim Levitsky 2021-05-10 15:13 ` Sean Christopherson 2021-05-11 12:34 ` Maxim Levitsky 2021-05-11 20:10 ` Sean Christopherson 2021-05-04 17:17 ` [PATCH 09/15] KVM: VMX: Use flag to indicate "active" uret MSRs instead of sorting list Sean Christopherson 2021-05-08 3:31 ` Reiji Watanabe 2021-05-10 16:43 ` Sean Christopherson 2021-05-10 17:55 ` Reiji Watanabe 2021-05-10 8:25 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 10/15] KVM: VMX: Use common x86's uret MSR list as the one true list Sean Christopherson 2021-05-10 8:25 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 11/15] KVM: VMX: Disable loading of TSX_CTRL MSR the more conventional way Sean Christopherson 2021-05-05 8:49 ` Paolo Bonzini 2021-05-05 15:36 ` Sean Christopherson 2021-05-05 15:50 ` Paolo Bonzini [this message] 2021-05-10 8:26 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 12/15] KVM: x86: Export the number of uret MSRs to vendor modules Sean Christopherson 2021-05-10 8:27 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 13/15] KVM: x86: Move uret MSR slot management to common x86 Sean Christopherson 2021-05-10 8:28 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 14/15] KVM: x86: Tie Intel and AMD behavior for MSR_TSC_AUX to guest CPU model Sean Christopherson 2021-05-10 8:29 ` Maxim Levitsky 2021-05-10 16:50 ` Sean Christopherson 2021-05-10 17:11 ` Jim Mattson 2021-05-11 12:34 ` Maxim Levitsky 2021-05-04 17:17 ` [PATCH 15/15] KVM: x86: Hide RDTSCP and RDPID if MSR_TSC_AUX probing failed Sean Christopherson 2021-05-10 8:29 ` Maxim Levitsky 2021-05-05 8:51 ` [PATCH 00/15] KVM: x86: RDPID/RDTSCP fixes and uret MSR cleanups Paolo Bonzini
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