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linux/arch/x86/kvm/governed_features.h

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KVM: x86: Add a framework for enabling KVM-governed x86 features Introduce yet another X86_FEATURE flag framework to manage and cache KVM governed features (for lack of a better name). "Governed" in this case means that KVM has some level of involvement and/or vested interest in whether or not an X86_FEATURE can be used by the guest. The intent of the framework is twofold: to simplify caching of guest CPUID flags that KVM needs to frequently query, and to add clarity to such caching, e.g. it isn't immediately obvious that SVM's bundle of flags for "optional nested SVM features" track whether or not a flag is exposed to L1. Begrudgingly define KVM_MAX_NR_GOVERNED_FEATURES for the size of the bitmap to avoid exposing governed_features.h in arch/x86/include/asm/, but add a FIXME to call out that it can and should be cleaned up once "struct kvm_vcpu_arch" is no longer expose to the kernel at large. Cc: Zeng Guang <guang.zeng@intel.com> Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com> Reviewed-by: Kai Huang <kai.huang@intel.com> Reviewed-by: Yuan Yao <yuan.yao@intel.com> Link: https://lore.kernel.org/r/20230815203653.519297-2-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:39 -07:00
/* SPDX-License-Identifier: GPL-2.0 */
#if !defined(KVM_GOVERNED_FEATURE) || defined(KVM_GOVERNED_X86_FEATURE)
BUILD_BUG()
#endif
#define KVM_GOVERNED_X86_FEATURE(x) KVM_GOVERNED_FEATURE(X86_FEATURE_##x)
KVM: x86/mmu: Use KVM-governed feature framework to track "GBPAGES enabled" Use the governed feature framework to track whether or not the guest can use 1GiB pages, and drop the one-off helper that wraps the surprisingly non-trivial logic surrounding 1GiB page usage in the guest. No functional change intended. Reviewed-by: Yuan Yao <yuan.yao@intel.com> Link: https://lore.kernel.org/r/20230815203653.519297-3-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:40 -07:00
KVM_GOVERNED_X86_FEATURE(GBPAGES)
KVM: x86: Use KVM-governed feature framework to track "XSAVES enabled" Use the governed feature framework to track if XSAVES is "enabled", i.e. if XSAVES can be used by the guest. Add a comment in the SVM code to explain the very unintuitive logic of deliberately NOT checking if XSAVES is enumerated in the guest CPUID model. No functional change intended. Reviewed-by: Yuan Yao <yuan.yao@intel.com> Link: https://lore.kernel.org/r/20230815203653.519297-7-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:44 -07:00
KVM_GOVERNED_X86_FEATURE(XSAVES)
KVM: nVMX: Use KVM-governed feature framework to track "nested VMX enabled" Track "VMX exposed to L1" via a governed feature flag instead of using a dedicated helper to provide the same functionality. The main goal is to drive convergence between VMX and SVM with respect to querying features that are controllable via module param (SVM likes to cache nested features), avoiding the guest CPUID lookups at runtime is just a bonus and unlikely to provide any meaningful performance benefits. Note, X86_FEATURE_VMX is set in kvm_cpu_caps if and only if "nested" is true, and the CPU obviously supports VMX if KVM+VMX is running. I.e. the check on "nested" is now implicitly down by the kvm_cpu_cap_has() check in kvm_governed_feature_check_and_set(). No functional change intended. Reviewed-by: Yuan Yao <yuan.yao@intel.com> Reviwed-by: Kai Huang <kai.huang@intel.com> Link: https://lore.kernel.org/r/20230815203653.519297-8-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:45 -07:00
KVM_GOVERNED_X86_FEATURE(VMX)
KVM: nSVM: Use KVM-governed feature framework to track "NRIPS enabled" Track "NRIPS exposed to L1" via a governed feature flag instead of using a dedicated bit/flag in vcpu_svm. No functional change intended. Reviewed-by: Yuan Yao <yuan.yao@intel.com> Link: https://lore.kernel.org/r/20230815203653.519297-9-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:46 -07:00
KVM_GOVERNED_X86_FEATURE(NRIPS)
KVM: nSVM: Use KVM-governed feature framework to track "TSC scaling enabled" Track "TSC scaling exposed to L1" via a governed feature flag instead of using a dedicated bit/flag in vcpu_svm. Note, this fixes a benign bug where KVM would mark TSC scaling as exposed to L1 even if overall nested SVM supported is disabled, i.e. KVM would let L1 write MSR_AMD64_TSC_RATIO even when KVM didn't advertise TSCRATEMSR support to userspace. Reviewed-by: Yuan Yao <yuan.yao@intel.com> Link: https://lore.kernel.org/r/20230815203653.519297-10-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:47 -07:00
KVM_GOVERNED_X86_FEATURE(TSCRATEMSR)
KVM: nSVM: Use KVM-governed feature framework to track "vVM{SAVE,LOAD} enabled" Track "virtual VMSAVE/VMLOAD exposed to L1" via a governed feature flag instead of using a dedicated bit/flag in vcpu_svm. Opportunistically add a comment explaining why KVM disallows virtual VMLOAD/VMSAVE when the vCPU model is Intel. No functional change intended. Link: https://lore.kernel.org/r/20230815203653.519297-11-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:48 -07:00
KVM_GOVERNED_X86_FEATURE(V_VMSAVE_VMLOAD)
KVM: nSVM: Use KVM-governed feature framework to track "LBRv enabled" Track "LBR virtualization exposed to L1" via a governed feature flag instead of using a dedicated bit/flag in vcpu_svm. Note, checking KVM's capabilities instead of the "lbrv" param means that the code isn't strictly equivalent, as lbrv_enabled could have been set if nested=false where as that the governed feature cannot. But that's a glorified nop as the feature/flag is consumed only by paths that are gated by nSVM being enabled. Link: https://lore.kernel.org/r/20230815203653.519297-12-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:49 -07:00
KVM_GOVERNED_X86_FEATURE(LBRV)
KVM: nSVM: Use KVM-governed feature framework to track "Pause Filter enabled" Track "Pause Filtering is exposed to L1" via governed feature flags instead of using dedicated bits/flags in vcpu_svm. No functional change intended. Reviewed-by: Yuan Yao <yuan.yao@intel.com> Link: https://lore.kernel.org/r/20230815203653.519297-13-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:50 -07:00
KVM_GOVERNED_X86_FEATURE(PAUSEFILTER)
KVM_GOVERNED_X86_FEATURE(PFTHRESHOLD)
KVM: nSVM: Use KVM-governed feature framework to track "vGIF enabled" Track "virtual GIF exposed to L1" via a governed feature flag instead of using a dedicated bit/flag in vcpu_svm. Note, checking KVM's capabilities instead of the "vgif" param means that the code isn't strictly equivalent, as vgif_enabled could have been set if nested=false where as that the governed feature cannot. But that's a glorified nop as the feature/flag is consumed only by paths that are Link: https://lore.kernel.org/r/20230815203653.519297-14-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:51 -07:00
KVM_GOVERNED_X86_FEATURE(VGIF)
KVM: nSVM: Use KVM-governed feature framework to track "vNMI enabled" Track "virtual NMI exposed to L1" via a governed feature flag instead of using a dedicated bit/flag in vcpu_svm. Note, checking KVM's capabilities instead of the "vnmi" param means that the code isn't strictly equivalent, as vnmi_enabled could have been set if nested=false where as that the governed feature cannot. But that's a glorified nop as the feature/flag is consumed only by paths that are gated by nSVM being enabled. Link: https://lore.kernel.org/r/20230815203653.519297-15-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:52 -07:00
KVM_GOVERNED_X86_FEATURE(VNMI)
KVM: x86: Use KVM-governed feature framework to track "LAM enabled" Use the governed feature framework to track if Linear Address Masking (LAM) is "enabled", i.e. if LAM can be used by the guest. Using the framework to avoid the relative expensive call guest_cpuid_has() during cr3 and vmexit handling paths for LAM. No functional change intended. Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com> Tested-by: Xuelian Guo <xuelian.guo@intel.com> Link: https://lore.kernel.org/r/20230913124227.12574-14-binbin.wu@linux.intel.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-09-13 05:42:24 -07:00
KVM_GOVERNED_X86_FEATURE(LAM)
KVM: x86/mmu: Use KVM-governed feature framework to track "GBPAGES enabled" Use the governed feature framework to track whether or not the guest can use 1GiB pages, and drop the one-off helper that wraps the surprisingly non-trivial logic surrounding 1GiB page usage in the guest. No functional change intended. Reviewed-by: Yuan Yao <yuan.yao@intel.com> Link: https://lore.kernel.org/r/20230815203653.519297-3-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:40 -07:00
KVM: x86: Add a framework for enabling KVM-governed x86 features Introduce yet another X86_FEATURE flag framework to manage and cache KVM governed features (for lack of a better name). "Governed" in this case means that KVM has some level of involvement and/or vested interest in whether or not an X86_FEATURE can be used by the guest. The intent of the framework is twofold: to simplify caching of guest CPUID flags that KVM needs to frequently query, and to add clarity to such caching, e.g. it isn't immediately obvious that SVM's bundle of flags for "optional nested SVM features" track whether or not a flag is exposed to L1. Begrudgingly define KVM_MAX_NR_GOVERNED_FEATURES for the size of the bitmap to avoid exposing governed_features.h in arch/x86/include/asm/, but add a FIXME to call out that it can and should be cleaned up once "struct kvm_vcpu_arch" is no longer expose to the kernel at large. Cc: Zeng Guang <guang.zeng@intel.com> Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com> Reviewed-by: Kai Huang <kai.huang@intel.com> Reviewed-by: Yuan Yao <yuan.yao@intel.com> Link: https://lore.kernel.org/r/20230815203653.519297-2-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-15 13:36:39 -07:00
#undef KVM_GOVERNED_X86_FEATURE
#undef KVM_GOVERNED_FEATURE
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