Re: [PATCH v13 19/85] KVM: Introduce kvm_follow_pfn() to eventually replace... | linuxppc-dev

[PATCH v13 00/85] KVM: Stop grabbing references to PFNMAP'd pages · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 01/85] KVM: Drop KVM_ERR_PTR_BAD_PAGE and instead return NULL to indicate an error · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 02/85] KVM: Allow calling kvm_release_page_{clean,dirty}() on a NULL page pointer · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 03/85] KVM: Add kvm_release_page_unused() API to put pages that KVM never consumes · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 04/85] KVM: x86/mmu: Skip the "try unsync" path iff the old SPTE was a leaf SPTE · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 05/85] KVM: x86/mmu: Don't overwrite shadow-present MMU SPTEs when prefaulting · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 06/85] KVM: x86/mmu: Invert @can_unsync and renamed to @synchronizing · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 07/85] KVM: x86/mmu: Mark new SPTE as Accessed when synchronizing existing SPTE · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 08/85] KVM: x86/mmu: Mark folio dirty when creating SPTE, not when zapping/modifying · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 09/85] KVM: x86/mmu: Mark page/folio accessed only when zapping leaf SPTEs · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 10/85] KVM: x86/mmu: Use gfn_to_page_many_atomic() when prefetching indirect PTEs · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 11/85] KVM: Rename gfn_to_page_many_atomic() to kvm_prefetch_pages() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 12/85] KVM: Drop @atomic param from gfn=>pfn and hva=>pfn APIs · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 13/85] KVM: Annotate that all paths in hva_to_pfn() might sleep · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 14/85] KVM: Return ERR_SIGPENDING from hva_to_pfn() if GUP returns -EGAIN · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 15/85] KVM: Drop extra GUP (via check_user_page_hwpoison()) to detect poisoned page · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 16/85] KVM: Replace "async" pointer in gfn=>pfn with "no_wait" and error code · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 17/85] KVM: x86/mmu: Drop kvm_page_fault.hva, i.e. don't track intermediate hva · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 18/85] KVM: Drop unused "hva" pointer from __gfn_to_pfn_memslot() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 19/85] KVM: Introduce kvm_follow_pfn() to eventually replace "gfn_to_pfn" APIs · Sean Christopherson <seanjc@google.com> · 2024-10-10
Re: [PATCH v13 19/85] KVM: Introduce kvm_follow_pfn() to eventually replace "gfn_to_pfn" APIs · Yan Zhao <hidden> · 2024-10-21
Re: [PATCH v13 19/85] KVM: Introduce kvm_follow_pfn() to eventually replace "gfn_to_pfn" APIs · Sean Christopherson <seanjc@google.com> · 2024-10-21
Re: [PATCH v13 19/85] KVM: Introduce kvm_follow_pfn() to eventually replace "gfn_to_pfn" APIs · Yan Zhao <hidden> · 2024-10-22
[PATCH v13 20/85] KVM: Remove pointless sanity check on @map param to kvm_vcpu_(un)map() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 21/85] KVM: Explicitly initialize all fields at the start of kvm_vcpu_map() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 22/85] KVM: Use NULL for struct page pointer to indicate mremapped memory · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 23/85] KVM: nVMX: Rely on kvm_vcpu_unmap() to track validity of eVMCS mapping · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 24/85] KVM: nVMX: Drop pointless msr_bitmap_map field from struct nested_vmx · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 25/85] KVM: nVMX: Add helper to put (unmap) vmcs12 pages · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 26/85] KVM: Use plain "struct page" pointer instead of single-entry array · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 27/85] KVM: Provide refcounted page as output field in struct kvm_follow_pfn · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 28/85] KVM: Move kvm_{set,release}_page_{clean,dirty}() helpers up in kvm_main.c · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 29/85] KVM: pfncache: Precisely track refcounted pages · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 30/85] KVM: Migrate kvm_vcpu_map() to kvm_follow_pfn() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 31/85] KVM: Pin (as in FOLL_PIN) pages during kvm_vcpu_map() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 32/85] KVM: nVMX: Mark vmcs12's APIC access page dirty when unmapping · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 33/85] KVM: Pass in write/dirty to kvm_vcpu_map(), not kvm_vcpu_unmap() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 34/85] KVM: Get writable mapping for __kvm_vcpu_map() only when necessary · Sean Christopherson <seanjc@google.com> · 2024-10-10
Re: [PATCH v13 34/85] KVM: Get writable mapping for __kvm_vcpu_map() only when necessary · Yan Zhao <hidden> · 2024-10-21
Re: [PATCH v13 34/85] KVM: Get writable mapping for __kvm_vcpu_map() only when necessary · Sean Christopherson <seanjc@google.com> · 2024-10-21
Re: [PATCH v13 34/85] KVM: Get writable mapping for __kvm_vcpu_map() only when necessary · Yan Zhao <hidden> · 2024-10-22
[PATCH v13 35/85] KVM: Disallow direct access (w/o mmu_notifier) to unpinned pfn by default · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 36/85] KVM: x86: Don't fault-in APIC access page during initial allocation · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 37/85] KVM: x86/mmu: Add "mmu" prefix fault-in helpers to free up generic names · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 38/85] KVM: x86/mmu: Put direct prefetched pages via kvm_release_page_clean() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 39/85] KVM: x86/mmu: Add common helper to handle prefetching SPTEs · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 40/85] KVM: x86/mmu: Add helper to "finish" handling a guest page fault · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 41/85] KVM: x86/mmu: Mark pages/folios dirty at the origin of make_spte() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 42/85] KVM: Move declarations of memslot accessors up in kvm_host.h · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 43/85] KVM: Add kvm_faultin_pfn() to specifically service guest page faults · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 44/85] KVM: x86/mmu: Convert page fault paths to kvm_faultin_pfn() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 45/85] KVM: guest_memfd: Pass index, not gfn, to __kvm_gmem_get_pfn() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 46/85] KVM: guest_memfd: Provide "struct page" as output from kvm_gmem_get_pfn() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 47/85] KVM: x86/mmu: Put refcounted pages instead of blindly releasing pfns · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 48/85] KVM: x86/mmu: Don't mark unused faultin pages as accessed · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 49/85] KVM: Move x86's API to release a faultin page to common KVM · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 50/85] KVM: VMX: Hold mmu_lock until page is released when updating APIC access page · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 51/85] KVM: VMX: Use __kvm_faultin_page() to get APIC access page/pfn · Sean Christopherson <seanjc@google.com> · 2024-10-10
Re: [PATCH v13 51/85] KVM: VMX: Use __kvm_faultin_page() to get APIC access page/pfn · Yan Zhao <hidden> · 2024-10-21
Re: [PATCH v13 51/85] KVM: VMX: Use __kvm_faultin_page() to get APIC access page/pfn · Sean Christopherson <seanjc@google.com> · 2024-10-21
Re: [PATCH v13 51/85] KVM: VMX: Use __kvm_faultin_page() to get APIC access page/pfn · Yan Zhao <hidden> · 2024-10-22
[PATCH v13 52/85] KVM: PPC: e500: Mark "struct page" dirty in kvmppc_e500_shadow_map() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 53/85] KVM: PPC: e500: Mark "struct page" pfn accessed before dropping mmu_lock · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 54/85] KVM: PPC: e500: Use __kvm_faultin_pfn() to handle page faults · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 55/85] KVM: arm64: Mark "struct page" pfns accessed/dirty before dropping mmu_lock · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 56/85] KVM: arm64: Use __kvm_faultin_pfn() to handle memory aborts · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 57/85] KVM: RISC-V: Mark "struct page" pfns dirty iff a stage-2 PTE is installed · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 58/85] KVM: RISC-V: Mark "struct page" pfns accessed before dropping mmu_lock · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 59/85] KVM: RISC-V: Use kvm_faultin_pfn() when mapping pfns into the guest · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 60/85] KVM: PPC: Use __kvm_faultin_pfn() to handle page faults on Book3s HV · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 61/85] KVM: PPC: Use __kvm_faultin_pfn() to handle page faults on Book3s Radix · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 62/85] KVM: PPC: Drop unused @kvm_ro param from kvmppc_book3s_instantiate_page() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 63/85] KVM: PPC: Book3S: Mark "struct page" pfns dirty/accessed after installing PTE · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 64/85] KVM: PPC: Use kvm_faultin_pfn() to handle page faults on Book3s PR · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 65/85] KVM: LoongArch: Mark "struct page" pfns dirty only in "slow" page fault path · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 66/85] KVM: LoongArch: Mark "struct page" pfns accessed only in "slow" page fault path · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 67/85] KVM: LoongArch: Mark "struct page" pfn accessed before dropping mmu_lock · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 68/85] KVM: LoongArch: Use kvm_faultin_pfn() to map pfns into the guest · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 69/85] KVM: MIPS: Mark "struct page" pfns dirty only in "slow" page fault path · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 70/85] KVM: MIPS: Mark "struct page" pfns accessed only in "slow" page fault path · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 71/85] KVM: MIPS: Mark "struct page" pfns accessed prior to dropping mmu_lock · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 72/85] KVM: MIPS: Use kvm_faultin_pfn() to map pfns into the guest · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 73/85] KVM: PPC: Remove extra get_page() to fix page refcount leak · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 74/85] KVM: PPC: Use kvm_vcpu_map() to map guest memory to patch dcbz instructions · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 75/85] KVM: Convert gfn_to_page() to use kvm_follow_pfn() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 76/85] KVM: Add support for read-only usage of gfn_to_page() · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 77/85] KVM: arm64: Use __gfn_to_page() when copying MTE tags to/from userspace · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 78/85] KVM: PPC: Explicitly require struct page memory for Ultravisor sharing · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 79/85] KVM: Drop gfn_to_pfn() APIs now that all users are gone · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 80/85] KVM: s390: Use kvm_release_page_dirty() to unpin "struct page" memory · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 81/85] KVM: Make kvm_follow_pfn.refcounted_page a required field · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 82/85] KVM: x86/mmu: Don't mark "struct page" accessed when zapping SPTEs · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 83/85] KVM: arm64: Don't mark "struct page" accessed when making SPTE young · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 84/85] KVM: Drop APIs that manipulate "struct page" via pfns · Sean Christopherson <seanjc@google.com> · 2024-10-10
[PATCH v13 85/85] KVM: Don't grab reference on VM_MIXEDMAP pfns that have a "struct page" · Sean Christopherson <seanjc@google.com> · 2024-10-10
Re: [PATCH v13 00/85] KVM: Stop grabbing references to PFNMAP'd pages · Paolo Bonzini <pbonzini@redhat.com> · 2024-10-17
Re: [PATCH v13 00/85] KVM: Stop grabbing references to PFNMAP'd pages · Sean Christopherson <seanjc@google.com> · 2024-10-22
Re: [PATCH v13 00/85] KVM: Stop grabbing references to PFNMAP'd pages · Paolo Bonzini <pbonzini@redhat.com> · 2024-10-25
Re: [PATCH v13 00/85] KVM: Stop grabbing references to PFNMAP'd pages · Dmitry Osipenko <dmitry.osipenko@collabora.com> · 2024-10-24

Re: [PATCH v13 19/85] KVM: Introduce kvm_follow_pfn() to eventually replace "gfn_to_pfn" APIs

From: Sean Christopherson <seanjc@google.com>
Date: 2024-10-21 18:08:51
Also in: kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-mips, linux-riscv, lkml, loongarch

On Mon, Oct 21, 2024, Yan Zhao wrote:

On Thu, Oct 10, 2024 at 11:23:21AM -0700, Sean Christopherson wrote:

quoted

--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c

@@ -159,6 +159,12 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc)
 	kvm_pfn_t new_pfn = KVM_PFN_ERR_FAULT;
 	void *new_khva = NULL;
 	unsigned long mmu_seq;
+	struct kvm_follow_pfn kfp = {
+		.slot = gpc->memslot,
+		.gfn = gpa_to_gfn(gpc->gpa),
+		.flags = FOLL_WRITE,
+		.hva = gpc->uhva,
+	};

Is .map_writable uninitialized?

Nope, per C99, "subobjects without explicit initializers are initialized to zero",
i.e. map_writable is initialized to "false".

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