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Message-ID: <20160414150652.GO30804@cbox>
Date: Thu, 14 Apr 2016 17:06:52 +0200
From: Christoffer Dall <christoffer.dall@...aro.org>
To: Suzuki K Poulose <suzuki.poulose@....com>
Cc: linux-arm-kernel@...ts.infradead.org, kvm@...r.kernel.org,
marc.zyngier@....com, mark.rutland@....com, will.deacon@....com,
catalin.marinas@....com, linux-kernel@...r.kernel.org,
kvmarm@...ts.cs.columbia.edu
Subject: Re: [PATCH v2 12/17] kvm-arm: Add explicit hyp page table modifiers
On Thu, Apr 14, 2016 at 02:21:00PM +0100, Suzuki K Poulose wrote:
> We have common routines to modify hyp and stage2 page tables
> based on the 'kvm' parameter. For a smoother transition to
> using separate routines for each, duplicate the routines
> and modify the copy to work on hyp.
>
> Marks the forked routines with _hyp_ and gets rid of the
> kvm parameter which is no longer needed and is NULL for hyp.
> Also, gets rid of calls to kvm_tlb_flush_by_vmid_ipa() calls
> from the hyp versions. Uses explicit host page table accessors
> instead of the kvm_* page table helpers.
>
> Suggested-by: Christoffer Dall <christoffer.dall@...aro.org>
> Cc: Marc Zyngier <marc.zyngier@....com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> ---
> Changes since V1:
> - Remove flush_dcache for !device_pfns in unmap_hyp_ptes()
> - Remove huge pmd/pud checks in unmap_hyp_p.ds, since we don't
> use huge mappings
> - Add a comment in unmap_hyp_range() on why we don't invalidate
> TLBs.
> ---
> arch/arm/kvm/mmu.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 99 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index f93f717..af526f6 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -388,6 +388,100 @@ static void stage2_flush_vm(struct kvm *kvm)
> srcu_read_unlock(&kvm->srcu, idx);
> }
>
> +static void clear_hyp_pgd_entry(pgd_t *pgd)
> +{
> + pud_t *pud_table __maybe_unused = pud_offset(pgd, 0UL);
> + pgd_clear(pgd);
> + pud_free(NULL, pud_table);
> + put_page(virt_to_page(pgd));
> +}
> +
> +static void clear_hyp_pud_entry(pud_t *pud)
> +{
> + pmd_t *pmd_table __maybe_unused = pmd_offset(pud, 0);
> + VM_BUG_ON(pud_huge(*pud));
> + pud_clear(pud);
> + pmd_free(NULL, pmd_table);
> + put_page(virt_to_page(pud));
> +}
> +
> +static void clear_hyp_pmd_entry(pmd_t *pmd)
> +{
> + pte_t *pte_table = pte_offset_kernel(pmd, 0);
> + VM_BUG_ON(pmd_thp_or_huge(*pmd));
> + pmd_clear(pmd);
> + pte_free_kernel(NULL, pte_table);
> + put_page(virt_to_page(pmd));
> +}
> +
> +static void unmap_hyp_ptes(pmd_t *pmd, phys_addr_t addr, phys_addr_t end)
> +{
> + pte_t *pte, *start_pte;
> +
> + start_pte = pte = pte_offset_kernel(pmd, addr);
> + do {
> + if (!pte_none(*pte)) {
> + kvm_set_pte(pte, __pte(0));
> + put_page(virt_to_page(pte));
> + }
> + } while (pte++, addr += PAGE_SIZE, addr != end);
> +
> + if (hyp_pte_table_empty(start_pte))
> + clear_hyp_pmd_entry(pmd);
> +}
> +
> +static void unmap_hyp_pmds(pud_t *pud, phys_addr_t addr, phys_addr_t end)
> +{
> + phys_addr_t next;
> + pmd_t *pmd, *start_pmd;
> +
> + start_pmd = pmd = pmd_offset(pud, addr);
> + do {
> + next = pmd_addr_end(addr, end);
> + /* Hyp doesn't use huge pmds */
> + if (!pmd_none(*pmd))
> + unmap_hyp_ptes(pmd, addr, next);
> + } while (pmd++, addr = next, addr != end);
> +
> + if (hyp_pmd_table_empty(start_pmd))
> + clear_hyp_pud_entry(pud);
> +}
> +
> +static void unmap_hyp_puds(pgd_t *pgd, phys_addr_t addr, phys_addr_t end)
> +{
> + phys_addr_t next;
> + pud_t *pud, *start_pud;
> +
> + start_pud = pud = pud_offset(pgd, addr);
> + do {
> + next = pud_addr_end(addr, end);
> + /* Hyp doesn't use huge puds */
> + if (!pud_none(*pud))
> + unmap_hyp_pmds(pud, addr, next);
> + } while (pud++, addr = next, addr != end);
> +
> + if (hyp_pud_table_empty(start_pud))
> + clear_hyp_pgd_entry(pgd);
> +}
> +
> +static void unmap_hyp_range(pgd_t *pgdp, phys_addr_t start, u64 size)
> +{
> + pgd_t *pgd;
> + phys_addr_t addr = start, end = start + size;
> + phys_addr_t next;
> +
> + /*
> + * We don't unmap anything from HYP, except at the hyp tear down.
> + * Hence, we don't have to invalidate the TLBs here.
> + */
> + pgd = pgdp + pgd_index(addr);
> + do {
> + next = pgd_addr_end(addr, end);
> + if (!pgd_none(*pgd))
> + unmap_hyp_puds(pgd, addr, next);
> + } while (pgd++, addr = next, addr != end);
> +}
> +
> /**
> * free_boot_hyp_pgd - free HYP boot page tables
> *
> @@ -398,14 +492,14 @@ void free_boot_hyp_pgd(void)
> mutex_lock(&kvm_hyp_pgd_mutex);
>
> if (boot_hyp_pgd) {
> - unmap_range(NULL, boot_hyp_pgd, hyp_idmap_start, PAGE_SIZE);
> - unmap_range(NULL, boot_hyp_pgd, TRAMPOLINE_VA, PAGE_SIZE);
> + unmap_hyp_range(boot_hyp_pgd, hyp_idmap_start, PAGE_SIZE);
> + unmap_hyp_range(boot_hyp_pgd, TRAMPOLINE_VA, PAGE_SIZE);
> free_pages((unsigned long)boot_hyp_pgd, hyp_pgd_order);
> boot_hyp_pgd = NULL;
> }
>
> if (hyp_pgd)
> - unmap_range(NULL, hyp_pgd, TRAMPOLINE_VA, PAGE_SIZE);
> + unmap_hyp_range(hyp_pgd, TRAMPOLINE_VA, PAGE_SIZE);
>
> mutex_unlock(&kvm_hyp_pgd_mutex);
> }
> @@ -430,9 +524,9 @@ void free_hyp_pgds(void)
>
> if (hyp_pgd) {
> for (addr = PAGE_OFFSET; virt_addr_valid(addr); addr += PGDIR_SIZE)
> - unmap_range(NULL, hyp_pgd, KERN_TO_HYP(addr), PGDIR_SIZE);
> + unmap_hyp_range(hyp_pgd, KERN_TO_HYP(addr), PGDIR_SIZE);
> for (addr = VMALLOC_START; is_vmalloc_addr((void*)addr); addr += PGDIR_SIZE)
> - unmap_range(NULL, hyp_pgd, KERN_TO_HYP(addr), PGDIR_SIZE);
> + unmap_hyp_range(hyp_pgd, KERN_TO_HYP(addr), PGDIR_SIZE);
>
> free_pages((unsigned long)hyp_pgd, hyp_pgd_order);
> hyp_pgd = NULL;
> --
> 1.7.9.5
>
Reviewed-by: Christoffer Dall <christoffer.dall@...aro.org>
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