- 09 Jul, 2020 28 commits
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Sean Christopherson authored
Don't bother filling the gfn array cache when the caller is a fully direct MMU, i.e. won't need a gfn array for shadow pages. Reviewed-by:
Ben Gardon <bgardon@google.com> Signed-off-by:
Sean Christopherson <sean.j.christopherson@intel.com> Message-Id: <20200703023545.8771-13-sean.j.christopherson@intel.com> Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com>
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Sean Christopherson authored
Set __GFP_ZERO for the shadow page memory cache and drop the explicit clear_page() from kvm_mmu_get_page(). This moves the cost of zeroing a page to the allocation time of the physical page, i.e. when topping up the memory caches, and thus avoids having to zero out an entire page while holding mmu_lock. Cc: Peter Feiner <pfeiner@google.com> Cc: Peter Shier <pshier@google.com> Cc: Junaid Shahid <junaids@google.com> Cc: Jim Mattson <jmattson@google.com> Suggested-by:
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Sean Christopherson authored
Add a gfp_zero flag to 'struct kvm_mmu_memory_cache' and use it to control __GFP_ZERO instead of hardcoding a call to kmem_cache_zalloc(). A future patch needs such a flag for the __get_free_page() path, as gfn arrays do not need/want the allocator to zero the memory. Convert the kmem_cache paths to __GFP_ZERO now so as to avoid a weird and inconsistent API in the future. No functional change intended. Reviewed-by:
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Sean Christopherson authored
Use separate caches for allocating shadow pages versus gfn arrays. This sets the stage for specifying __GFP_ZERO when allocating shadow pages without incurring extra cost for gfn arrays. No functional change intended. Reviewed-by:
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Sean Christopherson authored
Clean up the minimums in mmu_topup_memory_caches() to document the driving mechanisms behind the minimums. Now that encountering an empty cache is unlikely to trigger BUG_ON(), it is less dangerous to be more precise when defining the minimums. For rmaps, the logic is 1 parent PTE per level, plus a single rmap, and prefetched rmaps. The extra objects in the current '8 + PREFETCH' minimum came about due to an abundance of paranoia in commit c41ef344 ("KVM: MMU: increase per-vcpu rmap cache alloc size"), i.e. it could have increased the minimum to 2 rmaps. Furthermore, the unexpected extra rmap case was killed off entirely by commits f759e2b4 ("KVM: MMU: avoid pte_list_desc running out in kvm_mmu_pte_write") and f5a1e9f8 ("KVM: MMU: remove call to kvm_mmu_pte_write from walk_addr"). For the so called page cache, replace '8' with 2*PT64_ROOT_MAX_LEVEL. The 2x multiplier is needed because the cache is used for both shadow pages and gfn arrays for indirect MMUs. And finally, for page headers, replace '4' with PT64_ROOT_MAX_LEVEL. Note, KVM now supports 5-level paging, i.e. the old minimums that used a baseline derived from 4-level paging were technically wrong. But, KVM always allocates roots in a separate flow, e.g. it's impossible in the current implementation to actually need 5 new shadow pages in a single flow. Use PT64_ROOT_MAX_LEVEL unmodified instead of subtracting 1, as the direct usage is likely more intuitive to uninformed readers, and the inflated minimum is unlikely to affect functionality in practice. Reviewed-by:
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Sean Christopherson authored
Topup memory caches after walking the GVA->GPA translation during a shadow page fault, there is no need to ensure the caches are full when walking the GVA. As of commit f5a1e9f8 ("KVM: MMU: remove call to kvm_mmu_pte_write from walk_addr"), the FNAME(walk_addr) flow no longer add rmaps via kvm_mmu_pte_write(). This avoids allocating memory in the case that the GVA is unmapped in the guest, and also provides a paper trail of why/when the memory caches need to be filled. Reviewed-by:
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Sean Christopherson authored
Avoid refilling the memory caches and potentially slow reclaim/swap when handling a fast page fault, which does not need to allocate any new objects. Reviewed-by:
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Sean Christopherson authored
Attempt to allocate a new object instead of crashing KVM (and likely the kernel) if a memory cache is unexpectedly empty. Use GFP_ATOMIC for the allocation as the caches are used while holding mmu_lock. The immediate BUG_ON() makes the code unnecessarily explosive and led to confusing minimums being used in the past, e.g. allocating 4 objects where 1 would suffice. Reviewed-by:
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Sean Christopherson authored
Return errors directly from mmu_topup_memory_caches() instead of branching to a label that does the same. No functional change intended. Reviewed-by:
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Sean Christopherson authored
Use "mc" for local variables to shorten line lengths and provide consistent names, which will be especially helpful when some of the helpers are moved to common KVM code in future patches. No functional change intended. Reviewed-by:
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Sean Christopherson authored
Drop the "page" variants of the topup/free memory cache helpers, using the existence of an associated kmem_cache to select the correct alloc or free routine. No functional change intended. Reviewed-by:
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Sean Christopherson authored
Track the kmem_cache used for non-page KVM MMU memory caches instead of passing in the associated kmem_cache when filling the cache. This will allow consolidating code and other cleanups. No functional change intended. Reviewed-by:
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Thomas Gleixner authored
read/write_cr2() go throuh the paravirt XXL indirection, but nested VMX in a XEN_PV guest is not supported. Use the native variants. Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Message-Id: <20200708195322.344731916@linutronix.de> Signed-off-by:
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Thomas Gleixner authored
On guest exit MSR_GS_BASE contains whatever the guest wrote to it and the first action after returning from the ASM code is to set it to the host kernel value. This uses wrmsrl() which is interesting at least. wrmsrl() is either using native_write_msr() or the paravirt variant. The XEN_PV code is uninteresting as nested SVM in a XEN_PV guest does not work. But native_write_msr() can be placed out of line by the compiler especially when paravirtualization is enabled in the kernel configuration. The function is marked notrace, but still can be probed if CONFIG_KPROBE_EVENTS_ON_NOTRACE is enabled. That would be a fatal problem as kprobe events use per-CPU variables which are GS based and would be accessed with the guest GS. Depending on the GS value this would either explode in colorful ways or lead to completely undebugable data corruption. Aside of that native_write_msr() contains a tracepoint which objtool complains about as it is invoked from the noinstr section. As this cannot run inside a XEN_PV guest there is no point in using wrmsrl(). Use native_wrmsrl() instead which is just a plain native WRMSR without tracing or anything else attached. Signed-off-by:
Juergen Gross <jgross@suse.com> Message-Id: <20200708195322.244847377@linutronix.de> Signed-off-by:
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Thomas Gleixner authored
Move the functions which are inside the RCU off region into the non-instrumentable text section. Signed-off-by:
Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by:
Peter Zijlstra <peterz@infradead.org> Acked-by:
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Thomas Gleixner authored
Move the functions which are inside the RCU off region into the non-instrumentable text section. Signed-off-by:
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Thomas Gleixner authored
Entering guest mode is more or less the same as returning to user space. From an instrumentation point of view both leave kernel mode and the transition to guest or user mode reenables interrupts on the host. In user mode an interrupt is served directly and in guest mode it causes a VM exit which then handles or reinjects the interrupt. The transition from guest mode or user mode to kernel mode disables interrupts, which needs to be recorded in instrumentation to set the correct state again. This is important for e.g. latency analysis because otherwise the execution time in guest or user mode would be wrongly accounted as interrupt disabled and could trigger false positives. Add hardirq tracing to guest enter/exit functions in the same way as it is done in the user mode enter/exit code, respecting the RCU requirements. Signed-off-by:
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Thomas Gleixner authored
Entering guest mode is more or less the same as returning to user space. From an instrumentation point of view both leave kernel mode and the transition to guest or user mode reenables interrupts on the host. In user mode an interrupt is served directly and in guest mode it causes a VM exit which then handles or reinjects the interrupt. The transition from guest mode or user mode to kernel mode disables interrupts, which needs to be recorded in instrumentation to set the correct state again. This is important for e.g. latency analysis because otherwise the execution time in guest or user mode would be wrongly accounted as interrupt disabled and could trigger false positives. Add hardirq tracing to guest enter/exit functions in the same way as it is done in the user mode enter/exit code, respecting the RCU requirements. Signed-off-by:
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Thomas Gleixner authored
Context tracking for KVM happens way too early in the vcpu_run() code. Anything after guest_enter_irqoff() and before guest_exit_irqoff() cannot use RCU and should also be not instrumented. The current way of doing this covers way too much code. Move it closer to the actual vmenter/exit code. Signed-off-by:
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Maxim Levitsky authored
To avoid complex and in some cases incorrect logic in kvm_spec_ctrl_test_value, just try the guest's given value on the host processor instead, and if it doesn't #GP, allow the guest to set it. One such case is when host CPU supports STIBP mitigation but doesn't support IBRS (as is the case with some Zen2 AMD cpus), and in this case we were giving guest #GP when it tried to use STIBP The reason why can can do the host test is that IA32_SPEC_CTRL msr is passed to the guest, after the guest sets it to a non zero value for the first time (due to performance reasons), and as as result of this, it is pointless to emulate #GP condition on this first access, in a different way than what the host CPU does. This is based on a patch from Sean Christopherson, who suggested this idea. Fixes: 6441fa61 ("KVM: x86: avoid incorrect writes to host MSR_IA32_SPEC_CTRL") Cc: stable@vger.kernel.org Suggested-by:
Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20200708115731.180097-1-mlevitsk@redhat.com> Signed-off-by:
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Like Xu authored
In guest protected mode, if the current privilege level is not 0 and the PCE flag in the CR4 register is cleared, we will inject a #GP for RDPMC usage. Signed-off-by:
Like Xu <like.xu@linux.intel.com> Message-Id: <20200708074409.39028-1-like.xu@linux.intel.com> Signed-off-by:
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Vitaly Kuznetsov authored
OVMF booted guest running on shadow pages crashes on TRIPLE FAULT after enabling paging from SMM. The crash is triggered from mmu_check_root() and is caused by kvm_is_visible_gfn() searching through memslots with as_id = 0 while vCPU may be in a different context (address space). Introduce kvm_vcpu_is_visible_gfn() and use it from mmu_check_root(). Signed-off-by:
Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20200708140023.1476020-1-vkuznets@redhat.com> Signed-off-by:
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Xiaoyao Li authored
kvm_x86_ops.vcpu_after_set_cpuid() is used to update vmx/svm specific vcpu settings based on updated CPUID settings. So it's supposed to be called after CPUIDs are updated, i.e., kvm_update_cpuid_runtime(). Currently, kvm_update_cpuid_runtime() only updates CPUID bits of OSXSAVE, APIC, OSPKE, MWAIT, KVM_FEATURE_PV_UNHALT and CPUID(0xD,0).ebx and CPUID(0xD, 1).ebx. None of them is consumed by vmx/svm's update_vcpu_after_set_cpuid(). So there is no dependency between them. Move kvm_x86_ops.vcpu_after_set_cpuid() into kvm_vcpu_after_set_cpuid() is obviously more reasonable. Signed-off-by:
Xiaoyao Li <xiaoyao.li@intel.com> Message-Id: <20200709043426.92712-6-xiaoyao.li@intel.com> Signed-off-by:
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Xiaoyao Li authored
The name of callback cpuid_update() is misleading that it's not about updating CPUID settings of vcpu but updating the configurations of vcpu based on the CPUIDs. So rename it to vcpu_after_set_cpuid(). Signed-off-by:
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Xiaoyao Li authored
Now there is no updating CPUID bits behavior in kvm_update_cpuid(), rename it to kvm_vcpu_after_set_cpuid(). Signed-off-by:
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Xiaoyao Li authored
Beside called in kvm_vcpu_ioctl_set_cpuid*(), kvm_update_cpuid() is also called 5 places else in x86.c and 1 place else in lapic.c. All those 6 places only need the part of updating guest CPUIDs (OSXSAVE, OSPKE, APIC, KVM_FEATURE_PV_UNHALT, ...) based on the runtime vcpu state, so extract them as a separate kvm_update_cpuid_runtime(). Signed-off-by:
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Xiaoyao Li authored
Use kvm_check_cpuid() to validate if userspace provides legal cpuid settings and call it before KVM take any action to update CPUID or update vcpu states based on given CPUID settings. Signed-off-by:
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Xiaoyao Li authored
There is no dependencies between kvm_apic_set_version() and kvm_update_cpuid() because kvm_apic_set_version() queries X2APIC CPUID bit, which is not touched/changed by kvm_update_cpuid(). Obviously, kvm_apic_set_version() belongs to the category of updating vcpu model. Signed-off-by:
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- 08 Jul, 2020 12 commits
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Xiaoyao Li authored
Only code cleanup and no functional change. Signed-off-by:
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Xiaoyao Li authored
As handling of bits out of leaf 1 added over time, kvm_update_cpuid() should not return directly if leaf 1 is absent, but should go on updateing other CPUID leaves. Keep the update of apic->lapic_timer.timer_mode_mask in a separate wrapper, to minimize churn for code since it will be moved out of this function in a future patch. Signed-off-by:
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Xiaoyao Li authored
Current implementation keeps userspace input of CPUID configuration and cpuid->nent even if kvm_update_cpuid() fails. Reset vcpu->arch.cpuid_nent to 0 for the case of failure as a simple fix. Besides, update the doc to explicitly state that if IOCTL SET_CPUID* fail KVM gives no gurantee that previous valid CPUID configuration is kept. Signed-off-by:
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Like Xu authored
Some new Intel platforms (such as TGL) already have the fourth fixed counter TOPDOWN.SLOTS, but it has not been fully enabled on KVM and the host. Therefore, we limit edx.split.num_counters_fixed to 3, so that it does not break the kvm-unit-tests PMU test case and bad-handled userspace. Signed-off-by:
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Krish Sadhukhan authored
According to section "Canonicalization and Consistency Checks" in APM vol. 2 the following guest state is illegal: "Any MBZ bit of CR3 is set." "Any MBZ bit of CR4 is set." Suggeted-by:Krish Sadhukhan <krish.sadhukhan@oracle.com> Message-Id: <1594168797-29444-3-git-send-email-krish.sadhukhan@oracle.com> Signed-off-by:
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Paolo Bonzini authored
CR4.VMXE is reserved unless the VMX CPUID bit is set. On Intel, it is also tested by vmx_set_cr4, but AMD relies on kvm_valid_cr4, so fix it. Reviewed-by:
Jim Mattson <jmattson@google.com> Signed-off-by:
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Krish Sadhukhan authored
Instead of creating the mask for guest CR4 reserved bits in kvm_valid_cr4(), do it in kvm_update_cpuid() so that it can be reused instead of creating it each time kvm_valid_cr4() is called. Suggested-by:
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Jim Mattson authored
According to the SDM, when PAE paging would be in use following a MOV-to-CR0 that modifies any of CR0.CD, CR0.NW, or CR0.PG, then the PDPTEs are loaded from the address in CR3. Previously, kvm only loaded the PDPTEs when PAE paging would be in use following a MOV-to-CR0 that modified CR0.PG. Signed-off-by:
Oliver Upton <oupton@google.com> Reviewed-by:
Peter Shier <pshier@google.com> Message-Id: <20200707223630.336700-1-jmattson@google.com> Signed-off-by:
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Zhenzhong Duan authored
Map "xen_nopvspin" to "nopvspin", fix stale description of "xen_nopvspin" as we use qspinlock now. Signed-off-by:
Zhenzhong Duan <zhenzhong.duan@oracle.com> Reviewed-by:
Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Juergen Gross <jgross@suse.com> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by:
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Zhenzhong Duan authored
There are cases where a guest tries to switch spinlocks to bare metal behavior (e.g. by setting "xen_nopvspin" on XEN platform and "hv_nopvspin" on HYPER_V). That feature is missed on KVM, add a new parameter "nopvspin" to disable PV spinlocks for KVM guest. The new 'nopvspin' parameter will also replace Xen and Hyper-V specific parameters in future patches. Define variable nopvsin as global because it will be used in future patches as above. Signed-off-by:
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Zhenzhong Duan authored
pr_*() is preferred than printk(KERN_* ...), after change all the print in arch/x86/kernel/kvm.c will have "kvm-guest: xxx" style. No functional change. Signed-off-by:
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Zhenzhong Duan authored
This reverts commit 34226b6b. Commit 8990cac6 ("x86/jump_label: Initialize static branching early") adds jump_label_init() call in setup_arch() to make static keys initialized early, so we could use the original simpler code again. The similar change for XEN is in commit 090d54bc ("Revert "x86/paravirt: Set up the virt_spin_lock_key after static keys get initialized"") Signed-off-by:
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