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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id y10sm2523746ejh.105.2021.05.05.01.51.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 05 May 2021 01:51:51 -0700 (PDT) Subject: Re: [PATCH 00/15] KVM: x86: RDPID/RDTSCP fixes and uret MSR cleanups To: Sean Christopherson Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Reiji Watanabe References: <20210504171734.1434054-1-seanjc@google.com> From: Paolo Bonzini Message-ID: Date: Wed, 5 May 2021 10:51:49 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210504171734.1434054-1-seanjc@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 04/05/21 19:17, Sean Christopherson wrote: > This is a continuation of a less ambitious effort to unify MSR_TSC_AUX > handling across SVM and VMX. Reiji pointed out that MSR_TSC_AUX exists if > RDTSCP *or* RDPID is supported, and things went downhill from there. > > The first half of this series fixes a variety of RDTSCP and RDPID related > bugs. > > The second half of the series cleans up VMX's user return MSR framework > and consolidates more of the uret logic into common x86. > > The last two patches leverage the uret MSR cleanups to move MSR_TSC_AUX > handling to common x86 and add sanity checks to guard against misreporting > of RDPID and/or RDTSCP support. > > This will conflict with my vCPU RESET/INIT cleanup series. Feel free to > punt the conflicts to me. > > Other "fun" things to tackle: > > - The kernel proper also botches RDPID vs. RDTSCP, as MSR_TSC_AUX is > configured if RDTSCP is supported, but is consumed if RDPID is > supported. I'll send this fix separately. > > - Commit 844d69c26d83 ("KVM: SVM: Delay restoration of host MSR_TSC_AUX > until return to userspace") unwittingly fixed a bug where KVM would > write MSR_TSC_AUX with the guest's value when svm->guest_state_loaded > is false, which could lead to running the host with the guest's value. > The bug only exists in 5.12 (maybe 5.11 too?), so crafting a fix for > stable won't be too awful. > > Sean Christopherson (15): > KVM: VMX: Do not adverise RDPID if ENABLE_RDTSCP control is > unsupported > KVM: x86: Emulate RDPID only if RDTSCP is supported > KVM: SVM: Inject #UD on RDTSCP when it should be disabled in the guest > KVM: x86: Move RDPID emulation intercept to its own enum > KVM: VMX: Disable preemption when probing user return MSRs > KVM: SVM: Probe and load MSR_TSC_AUX regardless of RDTSCP support in > host > KVM: x86: Add support for RDPID without RDTSCP > KVM: VMX: Configure list of user return MSRs at module init > KVM: VMX: Use flag to indicate "active" uret MSRs instead of sorting > list > KVM: VMX: Use common x86's uret MSR list as the one true list > KVM: VMX: Disable loading of TSX_CTRL MSR the more conventional way > KVM: x86: Export the number of uret MSRs to vendor modules > KVM: x86: Move uret MSR slot management to common x86 > KVM: x86: Tie Intel and AMD behavior for MSR_TSC_AUX to guest CPU > model > KVM: x86: Hide RDTSCP and RDPID if MSR_TSC_AUX probing failed > > arch/x86/include/asm/kvm_host.h | 9 +- > arch/x86/kvm/cpuid.c | 18 ++- > arch/x86/kvm/emulate.c | 2 +- > arch/x86/kvm/kvm_emulate.h | 1 + > arch/x86/kvm/svm/svm.c | 50 +++----- > arch/x86/kvm/vmx/vmx.c | 217 ++++++++++++++++---------------- > arch/x86/kvm/vmx/vmx.h | 12 +- > arch/x86/kvm/x86.c | 101 ++++++++++++--- > 8 files changed, 245 insertions(+), 165 deletions(-) > Queued, thanks. Paolo