| Message ID | 59a1390923c40b0b83ae062e3041873292186577.1715971869.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Reimplement huge pages without hugepd on powerpc (8xx, e500, book3s/64) | expand |
On Fri, May 17, 2024 at 09:00:05PM +0200, Christophe Leroy wrote: > huge_pte_alloc() for non-HUGEPD targets is reserved for 8xx at the > moment. In order to convert other targets for non-HUGEPD, complement > huge_pte_alloc() to support any standard cont-PxD setup. > > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> > --- > arch/powerpc/mm/hugetlbpage.c | 25 ++++++++++++++++++++++++- > 1 file changed, 24 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c > index 42b12e1ec851..f8aefa1e7363 100644 > --- a/arch/powerpc/mm/hugetlbpage.c > +++ b/arch/powerpc/mm/hugetlbpage.c > @@ -195,11 +195,34 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, > pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, > unsigned long addr, unsigned long sz) > { > - pmd_t *pmd = pmd_off(mm, addr); > + pgd_t *pgd; > + p4d_t *p4d; > + pud_t *pud; > + pmd_t *pmd; > + > + addr &= ~(sz - 1); > + pgd = pgd_offset(mm, addr); > + > + p4d = p4d_offset(pgd, addr); > + if (sz >= PGDIR_SIZE) > + return (pte_t *)p4d; > + > + pud = pud_alloc(mm, p4d, addr); > + if (!pud) > + return NULL; > + if (sz >= PUD_SIZE) > + return (pte_t *)pud; > + > + pmd = pmd_alloc(mm, pud, addr); > + if (!pmd) > + return NULL; > > if (sz < PMD_SIZE) > return pte_alloc_huge(mm, pmd, addr, sz); > > + if (!IS_ENABLED(CONFIG_PPC_8xx)) > + return (pte_t *)pmd; So only 8xx has cont-PMD for hugepages? > + > if (sz != SZ_8M) > return NULL; Since this function is the core for allocation huge pages, I think it would benefit from a comment at the top explaining the possible layouts. e.g: Who can have cont-{P4d,PUD,PMD} etc. A brief explanation of the possible scheme for all powerpc platforms. That would help people looking into this in a future.
Le 25/05/2024 à 06:29, Oscar Salvador a écrit : > On Fri, May 17, 2024 at 09:00:05PM +0200, Christophe Leroy wrote: >> huge_pte_alloc() for non-HUGEPD targets is reserved for 8xx at the >> moment. In order to convert other targets for non-HUGEPD, complement >> huge_pte_alloc() to support any standard cont-PxD setup. >> >> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> >> --- >> arch/powerpc/mm/hugetlbpage.c | 25 ++++++++++++++++++++++++- >> 1 file changed, 24 insertions(+), 1 deletion(-) >> >> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c >> index 42b12e1ec851..f8aefa1e7363 100644 >> --- a/arch/powerpc/mm/hugetlbpage.c >> +++ b/arch/powerpc/mm/hugetlbpage.c >> @@ -195,11 +195,34 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, >> pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, >> unsigned long addr, unsigned long sz) >> { >> - pmd_t *pmd = pmd_off(mm, addr); >> + pgd_t *pgd; >> + p4d_t *p4d; >> + pud_t *pud; >> + pmd_t *pmd; >> + >> + addr &= ~(sz - 1); >> + pgd = pgd_offset(mm, addr); >> + >> + p4d = p4d_offset(pgd, addr); >> + if (sz >= PGDIR_SIZE) >> + return (pte_t *)p4d; >> + >> + pud = pud_alloc(mm, p4d, addr); >> + if (!pud) >> + return NULL; >> + if (sz >= PUD_SIZE) >> + return (pte_t *)pud; >> + >> + pmd = pmd_alloc(mm, pud, addr); >> + if (!pmd) >> + return NULL; >> >> if (sz < PMD_SIZE) >> return pte_alloc_huge(mm, pmd, addr, sz); >> >> + if (!IS_ENABLED(CONFIG_PPC_8xx)) >> + return (pte_t *)pmd; > > So only 8xx has cont-PMD for hugepages? No, all have cont-PMD but only 8xx handles pages greater than PMD_SIZE as cont-PTE instead of cont-PMD. > >> + >> if (sz != SZ_8M) >> return NULL; > > Since this function is the core for allocation huge pages, I think it would > benefit from a comment at the top explaining the possible layouts. > e.g: Who can have cont-{P4d,PUD,PMD} etc. > A brief explanation of the possible scheme for all powerpc platforms. All is standard except 8xx, let's just have a comment for 8xx. > > That would help people looking into this in a future. > > >
On Sat, May 25, 2024 at 06:44:06AM +0000, Christophe Leroy wrote: > No, all have cont-PMD but only 8xx handles pages greater than PMD_SIZE > as cont-PTE instead of cont-PMD. Yes, sorry, I managed to confuse myself. It is obvious from the code.
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c index 42b12e1ec851..f8aefa1e7363 100644 --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -195,11 +195,34 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, unsigned long sz) { - pmd_t *pmd = pmd_off(mm, addr); + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + + addr &= ~(sz - 1); + pgd = pgd_offset(mm, addr); + + p4d = p4d_offset(pgd, addr); + if (sz >= PGDIR_SIZE) + return (pte_t *)p4d; + + pud = pud_alloc(mm, p4d, addr); + if (!pud) + return NULL; + if (sz >= PUD_SIZE) + return (pte_t *)pud; + + pmd = pmd_alloc(mm, pud, addr); + if (!pmd) + return NULL; if (sz < PMD_SIZE) return pte_alloc_huge(mm, pmd, addr, sz); + if (!IS_ENABLED(CONFIG_PPC_8xx)) + return (pte_t *)pmd; + if (sz != SZ_8M) return NULL; if (!pte_alloc_huge(mm, pmd, addr, sz))
huge_pte_alloc() for non-HUGEPD targets is reserved for 8xx at the moment. In order to convert other targets for non-HUGEPD, complement huge_pte_alloc() to support any standard cont-PxD setup. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- arch/powerpc/mm/hugetlbpage.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-)