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([2001:b07:6468:f312:b99a:4374:773d:f32e]) by smtp.gmail.com with ESMTPSA id n3sm19656093wrv.91.2020.03.06.00.27.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 06 Mar 2020 00:27:49 -0800 (PST) Subject: Re: [PATCH v2 00/66] KVM: x86: Introduce KVM cpu caps To: Sean Christopherson Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiaoyao Li References: <20200302235709.27467-1-sean.j.christopherson@intel.com> From: Paolo Bonzini Message-ID: Date: Fri, 6 Mar 2020 09:27:48 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200302235709.27467-1-sean.j.christopherson@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/03/20 00:56, Sean Christopherson wrote: > Introduce what is effectively a KVM-specific copy of the x86_capabilities > array in boot_cpu_data, kvm_cpu_caps. kvm_cpu_caps is initialized by > copying boot_cpu_data.x86_capabilities before ->hardware_setup(). It is > then updated by KVM's CPUID logic (both common x86 and VMX/SVM specific) > to adjust the caps to reflect the CPU that KVM will expose to the guest. > > Quick synopsis: > 1. Refactor the KVM_GET_SUPPORTED_CPUID stack to consolidate code, > remove crustiness, and set the stage for introducing kvm_cpu_caps. > > 2. Introduce cpuid_entry_*() accessors/mutators to automatically > handle retrieving the correct reg from a CPUID entry, and to audit > that the entry matches the reserve CPUID lookup entry. The > cpuid_entry_*() helpers make moving the code from common x86 to > vendor code much less risky. > > 3. Move CPUID adjustments to vendor code in preparation for kvm_cpu_caps, > which will be initialized at load time before the kvm_x86_ops hooks > are ready to be used, i.e. before ->hardware_setup(). > > 4. Introduce kvm_cpu_caps and move all the CPUID code over to kvm_cpu_caps. > > 5. Use kvm_cpu_cap_has() to kill off a bunch of ->*_supported() hooks. > > 6. Additional cleanup in tangentially related areas to kill off even more > ->*_supported() hooks, including ->set_supported_cpuid(). > > Tested by verifying the output of KVM_GET_SUPPORTED_CPUID is identical > before and after on every patch on a Haswell and Coffee Lake, and for the > "before vs. after" output on Ice Lake. > > Verified correctness when hiding features via Qemu (running this version > of KVM in L1), e.g. that UMIP is correctly emulated for L2 when it's > hidden from L1, on relevant patches. > > Boot tested and ran kvm-unit-tests at key points, e.g. large page > handling. > > All AMD patches are build-tested only. I put the complete series on the cpu-caps branch of kvm.git. Thanks, Paolo > v2: > - Opportunistically remove bare "unsigned" usgae. [Vitaly] > - Remove CPUID auditing (Vitaly and Paolo suggested making it > unconditional, then I realized it would trigger false positives). > - Fix a bug in the series that broke SVM features enumeration. > - Only advertise SVM features when nested SVM is enabled. [Paolo] > - Fully remove support for stateful CPUID.0x2. [Vitaly, Paolo] > - Call out in patch 01's changelog that it technically breaks the > ABI, but that no known VMM is affected. [Vitaly, Paolo] > - Use @function instead of hardcoding "2" for thes stateful code (which > eventually gets tossed anyways). [Vitaly] > - Move 0x8000000A into common code and kill ->set_supported_cpuid(). > [Vitaly] > - Call out the subtle emulation handling in ->set_supported_cpuid(), > which also gets tossed :-). [Vitaly] > - Fix the BUILG_BUG_ON() in patch 38. [Vitaly] > - Use !! to explicitly cast a u32 to a bool. [Vitaly, Paolo] > - Sort kvm_cpu_cap_mask() calls by leaf number, ascending. [Vitaly] > - Collect reviews. [Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, > Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, > Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, > Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, > Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, > Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, > Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, > Vitaly, Vitaly, Vitaly, Vitaly, Vitaly, Xiaoyao, Xiaoyao, Xiaoyao] > > Sean Christopherson (66): > KVM: x86: Return -E2BIG when KVM_GET_SUPPORTED_CPUID hits max entries > KVM: x86: Refactor loop around do_cpuid_func() to separate helper > KVM: x86: Simplify handling of Centaur CPUID leafs > KVM: x86: Clean up error handling in kvm_dev_ioctl_get_cpuid() > KVM: x86: Check userapce CPUID array size after validating sub-leaf > KVM: x86: Move CPUID 0xD.1 handling out of the index>0 loop > KVM: x86: Check for CPUID 0xD.N support before validating array size > KVM: x86: Warn on zero-size save state for valid CPUID 0xD.N sub-leaf > KVM: x86: Refactor CPUID 0xD.N sub-leaf entry creation > KVM: x86: Clean up CPUID 0x7 sub-leaf loop > KVM: x86: Drop the explicit @index from do_cpuid_7_mask() > KVM: x86: Drop redundant boot cpu checks on SSBD feature bits > KVM: x86: Consolidate CPUID array max num entries checking > KVM: x86: Hoist loop counter and terminator to top of > __do_cpuid_func() > KVM: x86: Refactor CPUID 0x4 and 0x8000001d handling > KVM: x86: Encapsulate CPUID entries and metadata in struct > KVM: x86: Drop redundant array size check > KVM: x86: Use common loop iterator when handling CPUID 0xD.N > KVM: VMX: Add helpers to query Intel PT mode > KVM: x86: Calculate the supported xcr0 mask at load time > KVM: x86: Use supported_xcr0 to detect MPX support > KVM: x86: Make kvm_mpx_supported() an inline function > KVM: x86: Clear output regs for CPUID 0x14 if PT isn't exposed to > guest > KVM: x86: Drop explicit @func param from ->set_supported_cpuid() > KVM: x86: Use u32 for holding CPUID register value in helpers > KVM: x86: Replace bare "unsigned" with "unsigned int" in cpuid helpers > KVM: x86: Introduce cpuid_entry_{get,has}() accessors > KVM: x86: Introduce cpuid_entry_{change,set,clear}() mutators > KVM: x86: Refactor cpuid_mask() to auto-retrieve the register > KVM: x86: Handle MPX CPUID adjustment in VMX code > KVM: x86: Handle INVPCID CPUID adjustment in VMX code > KVM: x86: Handle UMIP emulation CPUID adjustment in VMX code > KVM: x86: Handle PKU CPUID adjustment in VMX code > KVM: x86: Handle RDTSCP CPUID adjustment in VMX code > KVM: x86: Handle Intel PT CPUID adjustment in VMX code > KVM: x86: Handle GBPAGE CPUID adjustment for EPT in VMX code > KVM: x86: Refactor handling of XSAVES CPUID adjustment > KVM: x86: Introduce kvm_cpu_caps to replace runtime CPUID masking > KVM: SVM: Convert feature updates from CPUID to KVM cpu caps > KVM: VMX: Convert feature updates from CPUID to KVM cpu caps > KVM: x86: Move XSAVES CPUID adjust to VMX's KVM cpu cap update > KVM: x86: Add a helper to check kernel support when setting cpu cap > KVM: x86: Use KVM cpu caps to mark CR4.LA57 as not-reserved > KVM: x86: Use KVM cpu caps to track UMIP emulation > KVM: x86: Fold CPUID 0x7 masking back into __do_cpuid_func() > KVM: x86: Remove the unnecessary loop on CPUID 0x7 sub-leafs > KVM: x86: Squash CPUID 0x2.0 insanity for modern CPUs > KVM: x86: Remove stateful CPUID handling > KVM: x86: Do host CPUID at load time to mask KVM cpu caps > KVM: x86: Override host CPUID results with kvm_cpu_caps > KVM: x86: Set emulated/transmuted feature bits via kvm_cpu_caps > KVM: x86: Use kvm_cpu_caps to detect Intel PT support > KVM: x86: Do kvm_cpuid_array capacity checks in terminal functions > KVM: x86: Use KVM cpu caps to detect MSR_TSC_AUX virt support > KVM: VMX: Directly use VMX capabilities helper to detect RDTSCP > support > KVM: x86: Check for Intel PT MSR virtualization using KVM cpu caps > KVM: VMX: Directly query Intel PT mode when refreshing PMUs > KVM: SVM: Refactor logging of NPT enabled/disabled > KVM: x86/mmu: Merge kvm_{enable,disable}_tdp() into a common function > KVM: x86/mmu: Configure max page level during hardware setup > KVM: x86: Don't propagate MMU lpage support to memslot.disallow_lpage > KVM: Drop largepages_enabled and its accessor/mutator > KVM: x86: Move VMX's host_efer to common x86 code > KVM: nSVM: Expose SVM features to L1 iff nested is enabled > KVM: nSVM: Advertise and enable NRIPS for L1 iff nrips is enabled > KVM: x86: Move nSVM CPUID 0x8000000A handing into common x86 code > > Documentation/virt/kvm/api.rst | 22 +- > arch/x86/include/asm/kvm_host.h | 15 +- > arch/x86/kvm/cpuid.c | 874 +++++++++++++++----------------- > arch/x86/kvm/cpuid.h | 134 ++++- > arch/x86/kvm/mmu/mmu.c | 29 +- > arch/x86/kvm/svm.c | 130 ++--- > arch/x86/kvm/vmx/capabilities.h | 25 +- > arch/x86/kvm/vmx/nested.c | 2 +- > arch/x86/kvm/vmx/pmu_intel.c | 2 +- > arch/x86/kvm/vmx/vmx.c | 121 +++-- > arch/x86/kvm/vmx/vmx.h | 5 +- > arch/x86/kvm/x86.c | 48 +- > arch/x86/kvm/x86.h | 10 +- > include/linux/kvm_host.h | 2 - > virt/kvm/kvm_main.c | 13 - > 15 files changed, 695 insertions(+), 737 deletions(-) >