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cf1d88b36b
It isn't OK to cache the dirty status of a page in internal structures for an indefinite period of time. Any time a vCPU exits the run loop to userspace might be its last; the VMM might do its final check of the dirty log, flush the last remaining dirty pages to the destination and complete a live migration. If we have internal 'dirty' state which doesn't get flushed until the vCPU is finally destroyed on the source after migration is complete, then we have lost data because that will escape the final copy. This problem already exists with the use of kvm_vcpu_unmap() to mark pages dirty in e.g. VMX nesting. Note that the actual Linux MM already considers the page to be dirty since we have a writeable mapping of it. This is just about the KVM dirty logging. For the nesting-style use cases (KVM_GUEST_USES_PFN) we will need to track which gfn_to_pfn_caches have been used and explicitly mark the corresponding pages dirty before returning to userspace. But we would have needed external tracking of that anyway, rather than walking the full list of GPCs to find those belonging to this vCPU which are dirty. So let's rely *solely* on that external tracking, and keep it simple rather than laying a tempting trap for callers to fall into. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20220303154127.202856-3-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
118 lines
2.6 KiB
C
118 lines
2.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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#ifndef __KVM_TYPES_H__
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#define __KVM_TYPES_H__
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struct kvm;
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struct kvm_async_pf;
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struct kvm_device_ops;
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struct kvm_interrupt;
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struct kvm_irq_routing_table;
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struct kvm_memory_slot;
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struct kvm_one_reg;
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struct kvm_run;
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struct kvm_userspace_memory_region;
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struct kvm_vcpu;
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struct kvm_vcpu_init;
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struct kvm_memslots;
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enum kvm_mr_change;
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#include <linux/bits.h>
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#include <linux/types.h>
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#include <linux/spinlock_types.h>
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#include <asm/kvm_types.h>
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/*
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* Address types:
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*
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* gva - guest virtual address
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* gpa - guest physical address
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* gfn - guest frame number
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* hva - host virtual address
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* hpa - host physical address
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* hfn - host frame number
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*/
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typedef unsigned long gva_t;
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typedef u64 gpa_t;
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typedef u64 gfn_t;
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#define GPA_INVALID (~(gpa_t)0)
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typedef unsigned long hva_t;
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typedef u64 hpa_t;
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typedef u64 hfn_t;
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typedef hfn_t kvm_pfn_t;
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enum pfn_cache_usage {
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KVM_GUEST_USES_PFN = BIT(0),
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KVM_HOST_USES_PFN = BIT(1),
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KVM_GUEST_AND_HOST_USE_PFN = KVM_GUEST_USES_PFN | KVM_HOST_USES_PFN,
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};
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struct gfn_to_hva_cache {
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u64 generation;
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gpa_t gpa;
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unsigned long hva;
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unsigned long len;
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struct kvm_memory_slot *memslot;
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};
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struct gfn_to_pfn_cache {
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u64 generation;
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gpa_t gpa;
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unsigned long uhva;
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struct kvm_memory_slot *memslot;
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struct kvm_vcpu *vcpu;
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struct list_head list;
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rwlock_t lock;
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void *khva;
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kvm_pfn_t pfn;
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enum pfn_cache_usage usage;
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bool active;
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bool valid;
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};
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#ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
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/*
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* Memory caches are used to preallocate memory ahead of various MMU flows,
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* e.g. page fault handlers. Gracefully handling allocation failures deep in
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* MMU flows is problematic, as is triggering reclaim, I/O, etc... while
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* holding MMU locks. Note, these caches act more like prefetch buffers than
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* classical caches, i.e. objects are not returned to the cache on being freed.
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*/
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struct kvm_mmu_memory_cache {
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int nobjs;
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gfp_t gfp_zero;
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struct kmem_cache *kmem_cache;
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void *objects[KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE];
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};
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#endif
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#define HALT_POLL_HIST_COUNT 32
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struct kvm_vm_stat_generic {
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u64 remote_tlb_flush;
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u64 remote_tlb_flush_requests;
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};
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struct kvm_vcpu_stat_generic {
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u64 halt_successful_poll;
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u64 halt_attempted_poll;
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u64 halt_poll_invalid;
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u64 halt_wakeup;
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u64 halt_poll_success_ns;
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u64 halt_poll_fail_ns;
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u64 halt_wait_ns;
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u64 halt_poll_success_hist[HALT_POLL_HIST_COUNT];
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u64 halt_poll_fail_hist[HALT_POLL_HIST_COUNT];
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u64 halt_wait_hist[HALT_POLL_HIST_COUNT];
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u64 blocking;
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};
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#define KVM_STATS_NAME_SIZE 48
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#endif /* __KVM_TYPES_H__ */
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