Re: [PATCH v6 04/19] powerpc: mm: Add p?d_large() definitions

From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Steven Price <steven.price@arm.com>, linux-mm@kvack.org
Cc: "Mark Rutland" <Mark.Rutland@arm.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Will Deacon" <will.deacon@arm.com>,
	"Paul Mackerras" <paulus@samba.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Liang, Kan" <kan.liang@linux.intel.com>,
	x86@kernel.org, "Ingo Molnar" <mingo@redhat.com>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	kvm-ppc@vger.kernel.org, "Jérôme Glisse" <jglisse@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"Andy Lutomirski" <luto@kernel.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	linux-arm-kernel@lists.infradead.org,
	"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	linux-kernel@vger.kernel.org, "James Morse" <james.morse@arm.com>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v6 04/19] powerpc: mm: Add p?d_large() definitions
Date: Tue, 26 Mar 2019 17:58:09 +0100	[thread overview]
Message-ID: <8a2efe07-b99f-3caa-fab9-47e49043bf66@c-s.fr> (raw)
In-Reply-To: <20190326162624.20736-5-steven.price@arm.com>

Le 26/03/2019 à 17:26, Steven Price a écrit :
> walk_page_range() is going to be allowed to walk page tables other than
> those of user space. For this it needs to know when it has reached a
> 'leaf' entry in the page tables. This information is provided by the
> p?d_large() functions/macros.
> 
> For powerpc pmd_large() was already implemented, so hoist it out of the
> CONFIG_TRANSPARENT_HUGEPAGE condition and implement the other levels.
> 
> Also since we now have a pmd_large always implemented we can drop the
> pmd_is_leaf() function.

Wouldn't it be better to drop the pmd_is_leaf() in a second patch ?

Christophe

> 
> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> CC: Paul Mackerras <paulus@samba.org>
> CC: Michael Ellerman <mpe@ellerman.id.au>
> CC: linuxppc-dev@lists.ozlabs.org
> CC: kvm-ppc@vger.kernel.org
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
>   arch/powerpc/include/asm/book3s/64/pgtable.h | 30 ++++++++++++++------
>   arch/powerpc/kvm/book3s_64_mmu_radix.c       | 12 ++------
>   2 files changed, 24 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index 581f91be9dd4..f6d1ac8b832e 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -897,6 +897,12 @@ static inline int pud_present(pud_t pud)
>   	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PRESENT));
>   }
>   
> +#define pud_large	pud_large
> +static inline int pud_large(pud_t pud)
> +{
> +	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
> +}
> +
>   extern struct page *pud_page(pud_t pud);
>   extern struct page *pmd_page(pmd_t pmd);
>   static inline pte_t pud_pte(pud_t pud)
> @@ -940,6 +946,12 @@ static inline int pgd_present(pgd_t pgd)
>   	return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PRESENT));
>   }
>   
> +#define pgd_large	pgd_large
> +static inline int pgd_large(pgd_t pgd)
> +{
> +	return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PTE));
> +}
> +
>   static inline pte_t pgd_pte(pgd_t pgd)
>   {
>   	return __pte_raw(pgd_raw(pgd));
> @@ -1093,6 +1105,15 @@ static inline bool pmd_access_permitted(pmd_t pmd, bool write)
>   	return pte_access_permitted(pmd_pte(pmd), write);
>   }
>   
> +#define pmd_large	pmd_large
> +/*
> + * returns true for pmd migration entries, THP, devmap, hugetlb
> + */
> +static inline int pmd_large(pmd_t pmd)
> +{
> +	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
> +}
> +
>   #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>   extern pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot);
>   extern pmd_t mk_pmd(struct page *page, pgprot_t pgprot);
> @@ -1119,15 +1140,6 @@ pmd_hugepage_update(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp,
>   	return hash__pmd_hugepage_update(mm, addr, pmdp, clr, set);
>   }
>   
> -/*
> - * returns true for pmd migration entries, THP, devmap, hugetlb
> - * But compile time dependent on THP config
> - */
> -static inline int pmd_large(pmd_t pmd)
> -{
> -	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
> -}
> -
>   static inline pmd_t pmd_mknotpresent(pmd_t pmd)
>   {
>   	return __pmd(pmd_val(pmd) & ~_PAGE_PRESENT);
> diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
> index f55ef071883f..1b57b4e3f819 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
> @@ -363,12 +363,6 @@ static void kvmppc_pte_free(pte_t *ptep)
>   	kmem_cache_free(kvm_pte_cache, ptep);
>   }
>   
> -/* Like pmd_huge() and pmd_large(), but works regardless of config options */
> -static inline int pmd_is_leaf(pmd_t pmd)
> -{
> -	return !!(pmd_val(pmd) & _PAGE_PTE);
> -}
> -
>   static pmd_t *kvmppc_pmd_alloc(void)
>   {
>   	return kmem_cache_alloc(kvm_pmd_cache, GFP_KERNEL);
> @@ -460,7 +454,7 @@ static void kvmppc_unmap_free_pmd(struct kvm *kvm, pmd_t *pmd, bool full,
>   	for (im = 0; im < PTRS_PER_PMD; ++im, ++p) {
>   		if (!pmd_present(*p))
>   			continue;
> -		if (pmd_is_leaf(*p)) {
> +		if (pmd_large(*p)) {
>   			if (full) {
>   				pmd_clear(p);
>   			} else {
> @@ -593,7 +587,7 @@ int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgtable, pte_t pte,
>   	else if (level <= 1)
>   		new_pmd = kvmppc_pmd_alloc();
>   
> -	if (level == 0 && !(pmd && pmd_present(*pmd) && !pmd_is_leaf(*pmd)))
> +	if (level == 0 && !(pmd && pmd_present(*pmd) && !pmd_large(*pmd)))
>   		new_ptep = kvmppc_pte_alloc();
>   
>   	/* Check if we might have been invalidated; let the guest retry if so */
> @@ -662,7 +656,7 @@ int kvmppc_create_pte(struct kvm *kvm, pgd_t *pgtable, pte_t pte,
>   		new_pmd = NULL;
>   	}
>   	pmd = pmd_offset(pud, gpa);
> -	if (pmd_is_leaf(*pmd)) {
> +	if (pmd_large(*pmd)) {
>   		unsigned long lgpa = gpa & PMD_MASK;
>   
>   		/* Check if we raced and someone else has set the same thing */
> 