On Wed, Oct 07, 2015 at 11:23:52AM +0100, Marc Zyngier wrote:
> On 15/09/15 16:41, Suzuki K. Poulose wrote:
> > From: "Suzuki K. Poulose" <suzuki.poulose@xxxxxxx>
> >
> > Rearrange the code for fake pgd handling, which is applicable
> > to only ARM64. The intention is to keep the common code cleaner,
> > unaware of the underlying hacks.
> >
> > Cc: kvmarm@xxxxxxxxxxxxxxxxxxxxx
> > Cc: christoffer.dall@xxxxxxxxxx
> > Cc: Marc.Zyngier@xxxxxxx
> > Signed-off-by: Suzuki K. Poulose <suzuki.poulose@xxxxxxx>
> > ---
> > arch/arm/include/asm/kvm_mmu.h | 7 ++++++
> > arch/arm/kvm/mmu.c | 44 +++++---------------------------------
> > arch/arm64/include/asm/kvm_mmu.h | 43 +++++++++++++++++++++++++++++++++++++
> > 3 files changed, 55 insertions(+), 39 deletions(-)
> >
> > diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
> > index 405aa18..1c9aa8a 100644
> > --- a/arch/arm/include/asm/kvm_mmu.h
> > +++ b/arch/arm/include/asm/kvm_mmu.h
> > @@ -173,6 +173,13 @@ static inline unsigned int kvm_get_hwpgd_size(void)
> > return PTRS_PER_S2_PGD * sizeof(pgd_t);
> > }
> >
> > +static inline pgd_t *kvm_setup_fake_pgd(pgd_t *pgd)
> > +{
> > + return pgd;
> > +}
> > +
> > +static inline void kvm_free_fake_pgd(pgd_t *pgd) {}
> > +
> > struct kvm;
> >
> > #define kvm_flush_dcache_to_poc(a,l) __cpuc_flush_dcache_area((a), (l))
> > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> > index 7b42012..b210622 100644
> > --- a/arch/arm/kvm/mmu.c
> > +++ b/arch/arm/kvm/mmu.c
> > @@ -677,43 +677,11 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm)
> > * guest, we allocate a fake PGD and pre-populate it to point
> > * to the next-level page table, which will be the real
> > * initial page table pointed to by the VTTBR.
> > - *
> > - * When KVM_PREALLOC_LEVEL==2, we allocate a single page for
> > - * the PMD and the kernel will use folded pud.
> > - * When KVM_PREALLOC_LEVEL==1, we allocate 2 consecutive PUD
> > - * pages.
> > */
> > - if (KVM_PREALLOC_LEVEL > 0) {
> > - int i;
> > -
> > - /*
> > - * Allocate fake pgd for the page table manipulation macros to
> > - * work. This is not used by the hardware and we have no
> > - * alignment requirement for this allocation.
> > - */
> > - pgd = kmalloc(PTRS_PER_S2_PGD * sizeof(pgd_t),
> > - GFP_KERNEL | __GFP_ZERO);
> > -
> > - if (!pgd) {
> > - kvm_free_hwpgd(hwpgd);
> > - return -ENOMEM;
> > - }
> > -
> > - /* Plug the HW PGD into the fake one. */
> > - for (i = 0; i < PTRS_PER_S2_PGD; i++) {
> > - if (KVM_PREALLOC_LEVEL == 1)
> > - pgd_populate(NULL, pgd + i,
> > - (pud_t *)hwpgd + i * PTRS_PER_PUD);
> > - else if (KVM_PREALLOC_LEVEL == 2)
> > - pud_populate(NULL, pud_offset(pgd, 0) + i,
> > - (pmd_t *)hwpgd + i * PTRS_PER_PMD);
> > - }
> > - } else {
> > - /*
> > - * Allocate actual first-level Stage-2 page table used by the
> > - * hardware for Stage-2 page table walks.
> > - */
> > - pgd = (pgd_t *)hwpgd;
> > + pgd = kvm_setup_fake_pgd(hwpgd);
> > + if (IS_ERR(pgd)) {
> > + kvm_free_hwpgd(hwpgd);
> > + return PTR_ERR(pgd);
> > }
> >
> > kvm_clean_pgd(pgd);
> > @@ -820,9 +788,7 @@ void kvm_free_stage2_pgd(struct kvm *kvm)
> >
> > unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE);
> > kvm_free_hwpgd(kvm_get_hwpgd(kvm));
> > - if (KVM_PREALLOC_LEVEL > 0)
> > - kfree(kvm->arch.pgd);
> > -
> > + kvm_free_fake_pgd(kvm->arch.pgd);
> > kvm->arch.pgd = NULL;
> > }
> >
> > diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
> > index 6150567..2567fe8 100644
> > --- a/arch/arm64/include/asm/kvm_mmu.h
> > +++ b/arch/arm64/include/asm/kvm_mmu.h
> > @@ -198,6 +198,49 @@ static inline unsigned int kvm_get_hwpgd_size(void)
> > return PTRS_PER_S2_PGD * sizeof(pgd_t);
> > }
> >
> > +/*
> > + * Allocate fake pgd for the page table manipulation macros to
> > + * work. This is not used by the hardware and we have no
> > + * alignment requirement for this allocation.
> > + */
> > +static inline pgd_t* kvm_setup_fake_pgd(pgd_t *hwpgd)
> > +{
> > + int i;
> > + pgd_t *pgd;
> > +
> > + if (!KVM_PREALLOC_LEVEL)
> > + return hwpgd;
> > + /*
> > + * When KVM_PREALLOC_LEVEL==2, we allocate a single page for
> > + * the PMD and the kernel will use folded pud.
> > + * When KVM_PREALLOC_LEVEL==1, we allocate 2 consecutive PUD
> > + * pages.
> > + */
> > + pgd = kmalloc(PTRS_PER_S2_PGD * sizeof(pgd_t),
> > + GFP_KERNEL | __GFP_ZERO);
> > +
> > + if (!pgd)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + /* Plug the HW PGD into the fake one. */
> > + for (i = 0; i < PTRS_PER_S2_PGD; i++) {
> > + if (KVM_PREALLOC_LEVEL == 1)
> > + pgd_populate(NULL, pgd + i,
> > + (pud_t *)hwpgd + i * PTRS_PER_PUD);
> > + else if (KVM_PREALLOC_LEVEL == 2)
> > + pud_populate(NULL, pud_offset(pgd, 0) + i,
> > + (pmd_t *)hwpgd + i * PTRS_PER_PMD);
> > + }
> > +
> > + return pgd;
> > +}
> > +
> > +static inline void kvm_free_fake_pgd(pgd_t *pgd)
> > +{
> > + if (KVM_PREALLOC_LEVEL > 0)
> > + kfree(pgd);
> > +}
> > +
> > static inline bool kvm_page_empty(void *ptr)
> > {
> > struct page *ptr_page = virt_to_page(ptr);
> >
>
> Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx>
I see we like moving this code around:
a987370 (arm64: KVM: Fix stage-2 PGD allocation to have per-page refcounting, 2015-03-10)
But I think the end result from this patch looks nice and it seems
correct to me:
Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Thanks,
-Christoffer
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