- 21 Apr, 2020 32 commits
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Sean Christopherson authored
Split the logic that determines whether a nested VM-Exit is reflected into L1 into "L0 wants" and "L1 wants" to document the core control flow at a high level. If L0 wants the VM-Exit, e.g. because the exit is due to a hardware event that isn't passed through to L1, then KVM should handle the exit in L0 without considering L1's configuration. Then, if L0 doesn't want the exit, KVM needs to query L1's wants to determine whether or not L1 "caused" the exit, e.g. by setting an exiting control, versus the exit occurring due to an L0 setting, e.g. when L0 intercepts an action that L1 chose to pass-through. Note, this adds an extra read on vmcs.VM_EXIT_INTR_INFO for exception. This will be addressed in a future patch via a VMX-wide enhancement, rather than pile on another case where vmx->exit_intr_info is conditionally available. Suggested-by:
Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by:
Sean Christopherson <sean.j.christopherson@intel.com> Message-Id: <20200415175519.14230-6-sean.j.christopherson@intel.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com>
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Sean Christopherson authored
Move the tracepoint for nested VM-Exits in preparation of splitting the reflection logic into L1 wants the exit vs. L0 always handles the exit. Signed-off-by:
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Sean Christopherson authored
Check for VM-Fail on nested VM-Enter in nested_vmx_reflect_vmexit() in preparation for separating nested_vmx_exit_reflected() into separate "L0 wants exit exit" and "L1 wants the exit" helpers. Explicitly set exit_intr_info and exit_qual to zero instead of reading them from vmcs02, as they are invalid on VM-Fail (and thankfully ignored by nested_vmx_vmexit() for nested VM-Fail). Signed-off-by:
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Sean Christopherson authored
Uninline nested_vmx_reflect_vmexit() in preparation of refactoring nested_vmx_exit_reflected() to split up the reflection logic into more consumable chunks, e.g. VM-Fail vs. L1 wants the exit vs. L0 always handles the exit. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Move the call to nested_vmx_exit_reflected() from vmx_handle_exit() into nested_vmx_reflect_vmexit() and change the semantics of the return value for nested_vmx_reflect_vmexit() to indicate whether or not the exit was reflected into L1. nested_vmx_exit_reflected() and nested_vmx_reflect_vmexit() are intrinsically tied together, calling one without simultaneously calling the other makes little sense. No functional change intended. Reviewed-by:
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Emanuele Giuseppe Esposito authored
The macros VM_STAT and VCPU_STAT are redundantly implemented in multiple files, each used by a different architecure to initialize the debugfs entries for statistics. Since they all have the same purpose, they can be unified in a single common definition in include/linux/kvm_host.h Signed-off-by:
Emanuele Giuseppe Esposito <eesposit@redhat.com> Message-Id: <20200414155625.20559-1-eesposit@redhat.com> Acked-by:
Cornelia Huck <cohuck@redhat.com> Signed-off-by:
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Paolo Bonzini authored
The placement of kvm_create_vcpu_debugfs is more or less irrelevant, since it cannot fail and userspace should not care about the debugfs entries until it knows the vcpu has been created. Moving it after the last failure point removes the need to remove the directory when unwinding the creation. Reviewed-by:
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Uros Bizjak authored
Use do_machine_check instead of INT $12 to pass MCE to the host, the same approach VMX uses. On a related note, there is no reason to limit the use of do_machine_check to 64 bit targets, as is currently done for VMX. MCE handling works for both target families. The patch is only compile tested, for both, 64 and 32 bit targets, someone should test the passing of the exception by injecting some MCEs into the guest. For future non-RFC patch, kvm_machine_check should be moved to some appropriate header file. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by:
Uros Bizjak <ubizjak@gmail.com> Message-Id: <20200411153627.3474710-1-ubizjak@gmail.com> Signed-off-by:
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Sean Christopherson authored
Rename @cr3 to @pgd in vmx_load_mmu_pgd() to reflect that it will be loaded into vmcs.EPT_POINTER and not vmcs.GUEST_CR3 when EPT is enabled. Similarly, load guest_cr3 with @pgd if and only if EPT is disabled. This fixes one of the last, if not _the_ last, cases in KVM where a variable that is not strictly a cr3 value uses "cr3" instead of "pgd". Signed-off-by:
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Sean Christopherson authored
Rename functions and variables in kvm_mmu_new_cr3() and related code to replace "cr3" with "pgd", i.e. continue the work started by commit 727a7e27 ("KVM: x86: rename set_cr3 callback and related flags to load_mmu_pgd"). kvm_mmu_new_cr3() and company are not always loading a new CR3, e.g. when nested EPT is enabled "cr3" is actually an EPTP. Signed-off-by:
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Sean Christopherson authored
Add logic to handle_invept() to free only those roots that match the target EPT context when emulating a single-context INVEPT. Signed-off-by:
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Sean Christopherson authored
Unconditionally skip the TLB flush triggered when reusing a root for a nested transition as nested_vmx_transition_tlb_flush() ensures the TLB is flushed when needed, regardless of whether the MMU can reuse a cached root (or the last root). Signed-off-by:
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Sean Christopherson authored
Skip the MMU sync when reusing a cached root if EPT is enabled or L1 enabled VPID for L2. If EPT is enabled, guest-physical mappings aren't flushed even if VPID is disabled, i.e. L1 can't expect stale TLB entries to be flushed if it has enabled EPT and L0 isn't shadowing PTEs (for L1 or L2) if L1 has EPT disabled. If VPID is enabled (and EPT is disabled), then L1 can't expect stale TLB entries to be flushed (for itself or L2). Signed-off-by:
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Sean Christopherson authored
Add a module param, flush_on_reuse, to override skip_tlb_flush and skip_mmu_sync when performing a so called "fast cr3 switch", i.e. when reusing a cached root. The primary motiviation for the control is to provide a fallback mechanism in the event that TLB flushing and/or MMU sync bugs are exposed/introduced by upcoming changes to stop unconditionally flushing on nested VMX transitions. Suggested-by:
Jim Mattson <jmattson@google.com> Suggested-by:
Junaid Shahid <junaids@google.com> Signed-off-by:
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Sean Christopherson authored
Add a separate "skip" override for MMU sync, a future change to avoid TLB flushes on nested VMX transitions may need to sync the MMU even if the TLB flush is unnecessary. Suggested-by:
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Sean Christopherson authored
Handle the side effects of a fast CR3 (PGD) switch up a level in __kvm_mmu_new_cr3(), which is the only caller of fast_cr3_switch(). This consolidates handling all side effects in __kvm_mmu_new_cr3() (where freeing the current root when KVM can't do a fast switch is already handled), and ameliorates the pain of adding a second boolean in a future patch to provide a separate "skip" override for the MMU sync. Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by:
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Sean Christopherson authored
Don't reload the APIC access page if its control is disabled, e.g. if the guest is running with x2APIC (likely) or with the local APIC disabled (unlikely), to avoid unnecessary TLB flushes and VMWRITEs. Unconditionally reload the APIC access page and flush the TLB when the guest's virtual APIC transitions to "xAPIC enabled", as any changes to the APIC access page's mapping will not be recorded while the guest's virtual APIC is disabled. Signed-off-by:
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Sean Christopherson authored
Move the retrieval of the HPA associated with L1's APIC access page into VMX code to avoid unnecessarily calling gfn_to_page(), e.g. when the vCPU is in guest mode (L2). Alternatively, the optimization logic in VMX could be mirrored into the common x86 code, but that will get ugly fast when further optimizations are introduced. Signed-off-by:
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Sean Christopherson authored
Defer reloading L1's APIC page by logging the need for a reload and processing it during nested VM-Exit instead of unconditionally reloading the APIC page on nested VM-Exit. This eliminates a TLB flush on the majority of VM-Exits as the APIC page rarely needs to be reloaded. Signed-off-by:
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Sean Christopherson authored
Flush only the current context, as opposed to all contexts, when requesting a TLB flush to handle the scenario where a L1 does not expect a TLB flush, but one is required because L1 and L2 shared an ASID. This occurs if EPT is disabled (no per-EPTP tag), VPID is enabled (hardware doesn't flush unconditionally) and vmcs02 does not have its own VPID due to exhaustion of available VPIDs. Signed-off-by:
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Sean Christopherson authored
Flush only the current ASID/context when requesting a TLB flush due to a change in the current vCPU's MMU to avoid blasting away TLB entries associated with other ASIDs/contexts, e.g. entries cached for L1 when a change in L2's MMU requires a flush. Signed-off-by:
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Sean Christopherson authored
Add KVM_REQ_TLB_FLUSH_CURRENT to allow optimized TLB flushing of VMX's EPTP/VPID contexts[*] from the KVM MMU and/or in a deferred manner, e.g. to flush L2's context during nested VM-Enter. Convert KVM_REQ_TLB_FLUSH to KVM_REQ_TLB_FLUSH_CURRENT in flows where the flush is directly associated with vCPU-scoped instruction emulation, i.e. MOV CR3 and INVPCID. Add a comment in vmx_vcpu_load_vmcs() above its KVM_REQ_TLB_FLUSH to make it clear that it deliberately requests a flush of all contexts. Service any pending flush request on nested VM-Exit as it's possible a nested VM-Exit could occur after requesting a flush for L2. Add the same logic for nested VM-Enter even though it's _extremely_ unlikely for flush to be pending on nested VM-Enter, but theoretically possible (in the future) due to RSM (SMM) emulation. [*] Intel also has an Address Space Identifier (ASID) concept, e.g. EPTP+VPID+PCID == ASID, it's just not documented in the SDM because the rules of invalidation are different based on which piece of the ASID is being changed, i.e. whether the EPTP, VPID, or PCID context must be invalidated. Signed-off-by: -
Sean Christopherson authored
Add a helper to determine whether or not a full TLB flush needs to be performed on nested VM-Enter/VM-Exit, as the logic is identical for both flows and needs a fairly beefy comment to boot. This also provides a common point to make future adjustments to the logic. Handle vpid12 changes the new helper as well even though it is specific to VM-Enter. The vpid12 logic is an extension of the flushing logic, and it's worth the extra bool parameter to provide a single location for the flushing logic. Cc: Liran Alon <liran.alon@oracle.com> Signed-off-by:
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Sean Christopherson authored
Rename ->tlb_flush() to ->tlb_flush_all() in preparation for adding a new hook to flush only the current ASID/context. Opportunstically replace the comment in vmx_flush_tlb() that explains why it flushes all EPTP/VPID contexts with a comment explaining why it unconditionally uses INVEPT when EPT is enabled. I.e. rely on the "all" part of the name to clarify why it does global INVEPT/INVVPID. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Add a comment in svm_flush_tlb() to document why it flushes only the current ASID, even when it is invoked when flushing remote TLBs. Cc: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by:
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Sean Christopherson authored
Add a helper to flush TLB entries only for the current EPTP/VPID context and use it for the existing direct invocations of vmx_flush_tlb(). TLB flushes that are specific to the current vCPU state do not need to flush other contexts. Note, both converted call sites happen to be related to the APIC access page, this is purely coincidental. Signed-off-by:
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Sean Christopherson authored
Move nested_get_vpid02() to vmx/nested.h so that a future patch can reference it from vmx.c to implement context-specific TLB flushing. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Move vmx_flush_tlb() to vmx.c and make it non-inline static now that all its callers live in vmx.c. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Use svm_flush_tlb() directly for kvm_x86_ops->tlb_flush_guest() now that the @invalidate_gpa param to ->tlb_flush() is gone, i.e. the wrapper for ->tlb_flush_guest() is no longer necessary. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Drop @invalidate_gpa from ->tlb_flush() and kvm_vcpu_flush_tlb() now that all callers pass %true for said param, or ignore the param (SVM has an internal call to svm_flush_tlb() in svm_flush_tlb_guest that somewhat arbitrarily passes %false). Remove __vmx_flush_tlb() as it is no longer used. No functional change intended. Signed-off-by:
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Sean Christopherson authored
Refactor vmx_flush_tlb_gva() to remove a superfluous local variable and clean up its comment, which is oddly located below the code it is commenting. No functional change intended. Reviewed-by:
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Vitaly Kuznetsov authored
Hyper-V PV TLB flush mechanism does TLB flush on behalf of the guest so doing tlb_flush_all() is an overkill, switch to using tlb_flush_guest() (just like KVM PV TLB flush mechanism) instead. Introduce KVM_REQ_HV_TLB_FLUSH to support the change. Signed-off-by:
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- 20 Apr, 2020 8 commits
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Sean Christopherson authored
Add a dedicated hook to handle flushing TLB entries on behalf of the guest, i.e. for a paravirtualized TLB flush, and use it directly instead of bouncing through kvm_vcpu_flush_tlb(). For VMX, change the effective implementation implementation to never do INVEPT and flush only the current context, i.e. to always flush via INVVPID(SINGLE_CONTEXT). The INVEPT performed by __vmx_flush_tlb() when @invalidate_gpa=false and enable_vpid=0 is unnecessary, as it will only flush guest-physical mappings; linear and combined mappings are flushed by VM-Enter when VPID is disabled, and changes in the guest pages tables do not affect guest-physical mappings. When EPT and VPID are enabled, doing INVVPID is not required (by Intel's architecture) to invalidate guest-physical mappings, i.e. TLB entries that cache guest-physical mappings can live across INVVPID as the mappings are associated with an EPTP, not a VPID. The intent of @invalidate_gpa is to inform vmx_flush_tlb() that it must "invalidate gpa mappings", i.e. do INVEPT and not simply INVVPID. Other than nested VPID handling, which now calls vpid_sync_context() directly, the only scenario where KVM can safely do INVVPID instead of INVEPT (when EPT is enabled) is if KVM is flushing TLB entries from the guest's perspective, i.e. is only required to invalidate linear mappings. For SVM, flushing TLB entries from the guest's perspective can be done by flushing the current ASID, as changes to the guest's page tables are associated only with the current ASID. Adding a dedicated ->tlb_flush_guest() paves the way toward removing @invalidate_gpa, which is a potentially dangerous control flag as its meaning is not exactly crystal clear, even for those who are familiar with the subtleties of what mappings Intel CPUs are/aren't allowed to keep across various invalidation scenarios. Signed-off-by:
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Sean Christopherson authored
Use vpid_sync_vcpu_addr() to emulate the "individual address" variant of INVVPID now that said function handles the fallback case of the (host) CPU not supporting "individual address". Note, the "vpid == 0" checks in the vpid_sync_*() helpers aren't actually redundant with the "!operand.vpid" check in handle_invvpid(), as the vpid passed to vpid_sync_vcpu_addr() is a KVM (host) controlled value, i.e. vpid02 can be zero even if operand.vpid is non-zero. No functional change intended. Reviewed-by:
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Sean Christopherson authored
Remove the INVVPID capabilities checks from vpid_sync_vcpu_single() and vpid_sync_vcpu_global() now that all callers ensure the INVVPID variant is supported. Note, in some cases the guarantee is provided in concert with hardware_setup(), which enables VPID if and only if at least of invvpid_single() or invvpid_global() is supported. Drop the WARN_ON_ONCE() from vmx_flush_tlb() as vpid_sync_vcpu_single() will trigger a WARN() on INVVPID failure, i.e. if SINGLE_CONTEXT isn't supported. Signed-off-by:
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Sean Christopherson authored
Directly invoke vpid_sync_context() to do a global INVVPID when the individual address variant is not supported instead of deferring such behavior to the caller. This allows for additional consolidation of code as the logic is basically identical to the emulation of the individual address variant in handle_invvpid(). No functional change intended. Reviewed-by:
Miaohe Lin <linmiaohe@huawei.com> Reviewed-by:
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Sean Christopherson authored
Move vpid_sync_vcpu_addr() below vpid_sync_context() so that it can be refactored in a future patch to call vpid_sync_context() directly when the "individual address" INVVPID variant isn't supported. No functional change intended. Reviewed-by:
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Sean Christopherson authored
Use vpid_sync_context() directly for flows that run if and only if enable_vpid=1, or more specifically, nested VMX flows that are gated by vmx->nested.msrs.secondary_ctls_high.SECONDARY_EXEC_ENABLE_VPID being set, which is allowed if and only if enable_vpid=1. Because these flows call __vmx_flush_tlb() with @invalidate_gpa=false, the if-statement that decides between INVEPT and INVVPID will always go down the INVVPID path, i.e. call vpid_sync_context() because "enable_ept && (invalidate_gpa || !enable_vpid)" always evaluates false. This helps pave the way toward removing @invalidate_gpa and @vpid from __vmx_flush_tlb() and its callers. Opportunstically drop unnecessary brackets in handle_invvpid() around an affected __vmx_flush_tlb()->vpid_sync_context() conversion. No functional change intended. Reviewed-by:
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Sean Christopherson authored
Skip the global INVVPID in the unlikely scenario that vpid==0 and the SINGLE_CONTEXT variant of INVVPID is unsupported. If vpid==0, there's no need to INVVPID as it's impossible to do VM-Enter with VPID enabled and vmcs.VPID==0, i.e. there can't be any TLB entries for the vCPU with vpid==0. The fact that the SINGLE_CONTEXT variant isn't supported is irrelevant. Signed-off-by:
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Junaid Shahid authored
When injecting a page fault or EPT violation/misconfiguration, KVM is not syncing any shadow PTEs associated with the faulting address, including those in previous MMUs that are associated with L1's current EPTP (in a nested EPT scenario), nor is it flushing any hardware TLB entries. All this is done by kvm_mmu_invalidate_gva. Page faults that are either !PRESENT or RSVD are exempt from the flushing, as the CPU is not allowed to cache such translations. Signed-off-by:
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