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Date: Fri, 21 Jul 2023 14:26:11 +0800
From: Yan Zhao <yan.y.zhao@...el.com>
To: Sean Christopherson <seanjc@...gle.com>
CC: Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>,
Oliver Upton <oliver.upton@...ux.dev>,
Huacai Chen <chenhuacai@...nel.org>,
Michael Ellerman <mpe@...erman.id.au>,
Anup Patel <anup@...infault.org>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
"Matthew Wilcox (Oracle)" <willy@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Paul Moore <paul@...l-moore.com>,
James Morris <jmorris@...ei.org>,
"Serge E. Hallyn" <serge@...lyn.com>, <kvm@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>, <kvmarm@...ts.linux.dev>,
<linux-mips@...r.kernel.org>, <linuxppc-dev@...ts.ozlabs.org>,
<kvm-riscv@...ts.infradead.org>, <linux-riscv@...ts.infradead.org>,
<linux-fsdevel@...r.kernel.org>, <linux-mm@...ck.org>,
<linux-security-module@...r.kernel.org>,
<linux-kernel@...r.kernel.org>,
Chao Peng <chao.p.peng@...ux.intel.com>,
Fuad Tabba <tabba@...gle.com>,
Jarkko Sakkinen <jarkko@...nel.org>,
Yu Zhang <yu.c.zhang@...ux.intel.com>,
Vishal Annapurve <vannapurve@...gle.com>,
Ackerley Tng <ackerleytng@...gle.com>,
Maciej Szmigiero <mail@...iej.szmigiero.name>,
Vlastimil Babka <vbabka@...e.cz>,
David Hildenbrand <david@...hat.com>,
Quentin Perret <qperret@...gle.com>,
Michael Roth <michael.roth@....com>,
Wang <wei.w.wang@...el.com>,
Liam Merwick <liam.merwick@...cle.com>,
"Isaku Yamahata" <isaku.yamahata@...il.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [RFC PATCH v11 01/29] KVM: Wrap kvm_gfn_range.pte in a
per-action union
On Tue, Jul 18, 2023 at 04:44:44PM -0700, Sean Christopherson wrote:
May I know why KVM now needs to register to callback .change_pte()?
As also commented in kvm_mmu_notifier_change_pte(), .change_pte() must be
surrounded by .invalidate_range_{start,end}().
While kvm_mmu_notifier_invalidate_range_start() has called kvm_unmap_gfn_range()
to zap all leaf SPTEs, and page fault path will not install new SPTEs
successfully before kvm_mmu_notifier_invalidate_range_end(),
kvm_set_spte_gfn() should not be able to find any shadow present leaf entries to
update PFN.
Or could we just delete completely
"kvm_handle_hva_range(mn, address, address + 1, pte, kvm_set_spte_gfn);"
from kvm_mmu_notifier_change_pte() ?
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 6db9ef288ec3..55f03a68f1cd 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1721,7 +1721,7 @@ bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
>
> bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
> {
> - kvm_pfn_t pfn = pte_pfn(range->pte);
> + kvm_pfn_t pfn = pte_pfn(range->arg.pte);
>
> if (!kvm->arch.mmu.pgt)
> return false;
> diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
> index e8c08988ed37..7b2ac1319d70 100644
> --- a/arch/mips/kvm/mmu.c
> +++ b/arch/mips/kvm/mmu.c
> @@ -447,7 +447,7 @@ bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
> bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
> {
> gpa_t gpa = range->start << PAGE_SHIFT;
> - pte_t hva_pte = range->pte;
> + pte_t hva_pte = range->arg.pte;
> pte_t *gpa_pte = kvm_mips_pte_for_gpa(kvm, NULL, gpa);
> pte_t old_pte;
>
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index f2eb47925806..857f4312b0f8 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -559,7 +559,7 @@ bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
> bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
> {
> int ret;
> - kvm_pfn_t pfn = pte_pfn(range->pte);
> + kvm_pfn_t pfn = pte_pfn(range->arg.pte);
>
> if (!kvm->arch.pgd)
> return false;
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index ec169f5c7dce..d72f2b20f430 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -1588,7 +1588,7 @@ static __always_inline bool kvm_handle_gfn_range(struct kvm *kvm,
> for_each_slot_rmap_range(range->slot, PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL,
> range->start, range->end - 1, &iterator)
> ret |= handler(kvm, iterator.rmap, range->slot, iterator.gfn,
> - iterator.level, range->pte);
> + iterator.level, range->arg.pte);
>
> return ret;
> }
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index 512163d52194..6250bd3d20c1 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -1241,7 +1241,7 @@ static bool set_spte_gfn(struct kvm *kvm, struct tdp_iter *iter,
> u64 new_spte;
>
> /* Huge pages aren't expected to be modified without first being zapped. */
> - WARN_ON(pte_huge(range->pte) || range->start + 1 != range->end);
> + WARN_ON(pte_huge(range->arg.pte) || range->start + 1 != range->end);
>
> if (iter->level != PG_LEVEL_4K ||
> !is_shadow_present_pte(iter->old_spte))
> @@ -1255,9 +1255,9 @@ static bool set_spte_gfn(struct kvm *kvm, struct tdp_iter *iter,
> */
> tdp_mmu_iter_set_spte(kvm, iter, 0);
>
> - if (!pte_write(range->pte)) {
> + if (!pte_write(range->arg.pte)) {
> new_spte = kvm_mmu_changed_pte_notifier_make_spte(iter->old_spte,
> - pte_pfn(range->pte));
> + pte_pfn(range->arg.pte));
>
> tdp_mmu_iter_set_spte(kvm, iter, new_spte);
> }
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