Lines Matching +full:first +full:- +full:generation
1 .. SPDX-License-Identifier: GPL-2.0
13 - correctness:
18 - security:
21 - performance:
23 - scaling:
25 - hardware:
27 - integration:
31 - dirty tracking:
33 and framebuffer-based displays
34 - footprint:
37 - reliability:
62 The mmu supports first-generation mmu hardware, which allows an atomic switch
64 two-dimensional paging (AMD's NPT and Intel's EPT). The emulated hardware
76 - when guest paging is disabled, we translate guest physical addresses to
77 host physical addresses (gpa->hpa)
78 - when guest paging is enabled, we translate guest virtual addresses, to
79 guest physical addresses, to host physical addresses (gva->gpa->hpa)
80 - when the guest launches a guest of its own, we translate nested guest
82 addresses, to host physical addresses (ngva->ngpa->gpa->hpa)
94 addresses (gpa->hva); note that two gpas may alias to the same hva, but not
108 - writes to control registers (especially cr3)
109 - invlpg/invlpga instruction execution
110 - access to missing or protected translations
114 - changes in the gpa->hpa translation (either through gpa->hva changes or
115 through hva->hpa changes)
116 - memory pressure (the shrinker)
133 The following table shows translations encoded by leaf ptes, with higher-level
136 Non-nested guests::
138 nonpaging: gpa->hpa
139 paging: gva->gpa->hpa
140 paging, tdp: (gva->)gpa->hpa
144 non-tdp: ngva->gpa->hpa (*)
145 tdp: (ngva->)ngpa->gpa->hpa
147 (*) the guest hypervisor will encode the ngva->gpa translation into its page
157 host pages, and gpa->hpa translations when NPT or EPT is active.
159 by role.level (2MB for first level, 1GB for second level, 0.5TB for third
164 When role.gpte_is_8_bytes=0, the guest uses 32-bit gptes while the host uses 64-bit
167 For first-level shadow pages, role.quadrant can be 0 or 1 and denotes the
168 first or second 512-gpte block in the guest page table. For second-level
169 page tables, each 32-bit gpte is converted to two 64-bit sptes
170 (since each first-level guest page is shadowed by two first-level
182 if 64-bit gptes are in use, '0' if 32-bit gptes are in use.
212 A pageful of 64-bit sptes containing the translations for this page.
214 The page pointed to by spt will have its page->private pointing back
216 sptes in spt point either at guest pages, or at lower-level shadow pages.
217 Specifically, if sp1 and sp2 are shadow pages, then sp1->spt[n] may point
218 at __pa(sp2->spt). sp2 will point back at sp1 through parent_pte.
250 Only present on 32-bit hosts, where a 64-bit spte cannot be written
252 to detect in-progress updates and retry them until the writer has
256 emulations if the page needs to be write-protected (see "Synchronized
259 possible for non-leafs. This field counts the number of emulations
296 - guest page fault (or npt page fault, or ept violation)
300 - a true guest fault (the guest translation won't allow the access) (*)
301 - access to a missing translation
302 - access to a protected translation
303 - when logging dirty pages, memory is write protected
304 - synchronized shadow pages are write protected (*)
305 - access to untranslatable memory (mmio)
311 - if the RSV bit of the error code is set, the page fault is caused by guest
314 - walk shadow page table
315 - check for valid generation number in the spte (see "Fast invalidation of
317 - cache the information to vcpu->arch.mmio_gva, vcpu->arch.mmio_access and
318 vcpu->arch.mmio_gfn, and call the emulator
320 - If both P bit and R/W bit of error code are set, this could possibly
324 - if needed, walk the guest page tables to determine the guest translation
325 (gva->gpa or ngpa->gpa)
327 - if permissions are insufficient, reflect the fault back to the guest
329 - determine the host page
331 - if this is an mmio request, there is no host page; cache the info to
332 vcpu->arch.mmio_gva, vcpu->arch.mmio_access and vcpu->arch.mmio_gfn
334 - walk the shadow page table to find the spte for the translation,
337 - If this is an mmio request, cache the mmio info to the spte and set some
340 - try to unsynchronize the page
342 - if successful, we can let the guest continue and modify the gpte
344 - emulate the instruction
346 - if failed, unshadow the page and let the guest continue
348 - update any translations that were modified by the instruction
352 - walk the shadow page hierarchy and drop affected translations
353 - try to reinstantiate the indicated translation in the hope that the
358 - mov to cr3
360 - look up new shadow roots
361 - synchronize newly reachable shadow pages
363 - mov to cr0/cr4/efer
365 - set up mmu context for new paging mode
366 - look up new shadow roots
367 - synchronize newly reachable shadow pages
371 - mmu notifier called with updated hva
372 - look up affected sptes through reverse map
373 - drop (or update) translations
387 - kernel write fault: spte.u=0, spte.w=1 (allows full kernel access,
389 - read fault: spte.u=1, spte.w=0 (allows full read access, disallows kernel
394 In the first case there are two additional complications:
396 - if CR4.SMEP is enabled: since we've turned the page into a kernel page,
401 - if CR4.SMAP is disabled: since the page has been changed to a kernel
410 with one value of cr0.wp cannot be used when cr0.wp has a different value -
426 - the spte must point to a large host page
427 - the guest pte must be a large pte of at least equivalent size (if tdp is
429 - if the spte will be writeable, the large page frame may not overlap any
430 write-protected pages
431 - the guest page must be wholly contained by a single memory slot
433 To check the last two conditions, the mmu maintains a ->disallow_lpage set of
437 artificially inflated ->disallow_lpages so they can never be instantiated.
449 generation number. The global generation number is stored in
450 kvm_memslots(kvm)->generation, and increased whenever guest memory info
453 When KVM finds an MMIO spte, it checks the generation number of the spte.
454 If the generation number of the spte does not equal the global generation
458 Since only 18 bits are used to store generation-number on mmio spte, all
462 times, the last one happening when the generation number is retrieved and
464 out-of-date information, but with an up-to-date generation number.
466 To avoid this, the generation number is incremented again after synchronize_srcu
467 returns; thus, bit 63 of kvm_memslots(kvm)->generation set to 1 only during a
469 want to use an MMIO sptes created with an odd generation number, and we can do
470 this without losing a bit in the MMIO spte. The "update in-progress" bit of the
471 generation is not stored in MMIO spte, and is so is implicitly zero when the
472 generation is extracted out of the spte. If KVM is unlucky and creates an MMIO
473 spte while an update is in-progress, the next access to the spte will always be
475 miss due to the in-progress flag diverging, while an access after the update
476 window closes will have a higher generation number (as compared to the spte).
482 - NPT presentation from KVM Forum 2008
483 https://www.linux-kvm.org/images/c/c8/KvmForum2008%24kdf2008_21.pdf