From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id BFB401A011D for ; Mon, 7 Mar 2016 16:31:00 +1100 (AEDT) Date: Mon, 7 Mar 2016 16:30:55 +1100 From: David Gibson To: Alexey Kardashevskiy Cc: linuxppc-dev@lists.ozlabs.org, Paul Mackerras , Alex Williamson , kvm-ppc@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH kernel 2/9] powerpc/mmu: Add real mode support for IOMMU preregistered memory Message-ID: <20160307053055.GK22546@voom.fritz.box> References: <1457322077-26640-1-git-send-email-aik@ozlabs.ru> <1457322077-26640-3-git-send-email-aik@ozlabs.ru> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Tv3+oRj6D9L8lW+H" In-Reply-To: <1457322077-26640-3-git-send-email-aik@ozlabs.ru> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --Tv3+oRj6D9L8lW+H Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Mar 07, 2016 at 02:41:10PM +1100, Alexey Kardashevskiy wrote: > This makes mm_iommu_lookup() able to work in realmode by replacing > list_for_each_entry_rcu() (which can do debug stuff which can fail in > real mode) with list_for_each_entry_lockless(). >=20 > This adds realmode version of mm_iommu_ua_to_hpa() which adds > explicit vmalloc'd-to-linear address conversion. > Unlike mm_iommu_ua_to_hpa(), mm_iommu_rm_ua_to_hpa() can fail. >=20 > This changes mm_iommu_preregistered() to receive @mm as in real mode > @current does not always have a correct pointer. So, I'd generally expect a parameter called @mm to be an mm_struct *, not a mm_context_t. >=20 > This adds realmode version of mm_iommu_lookup() which receives @mm > (for the same reason as for mm_iommu_preregistered()) and uses > lockless version of list_for_each_entry_rcu(). >=20 > Signed-off-by: Alexey Kardashevskiy > --- > arch/powerpc/include/asm/mmu_context.h | 6 ++++- > arch/powerpc/mm/mmu_context_iommu.c | 45 ++++++++++++++++++++++++++++= ++---- > 2 files changed, 45 insertions(+), 6 deletions(-) >=20 > diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/includ= e/asm/mmu_context.h > index 878c277..3ba652a 100644 > --- a/arch/powerpc/include/asm/mmu_context.h > +++ b/arch/powerpc/include/asm/mmu_context.h > @@ -18,7 +18,7 @@ extern void destroy_context(struct mm_struct *mm); > #ifdef CONFIG_SPAPR_TCE_IOMMU > struct mm_iommu_table_group_mem_t; > =20 > -extern bool mm_iommu_preregistered(void); > +extern bool mm_iommu_preregistered(mm_context_t *mm); > extern long mm_iommu_get(unsigned long ua, unsigned long entries, > struct mm_iommu_table_group_mem_t **pmem); > extern long mm_iommu_put(struct mm_iommu_table_group_mem_t *mem); > @@ -26,10 +26,14 @@ extern void mm_iommu_init(mm_context_t *ctx); > extern void mm_iommu_cleanup(mm_context_t *ctx); > extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long = ua, > unsigned long size); > +extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(mm_context_= t *mm, > + unsigned long ua, unsigned long size); > extern struct mm_iommu_table_group_mem_t *mm_iommu_find(unsigned long ua, > unsigned long entries); > extern long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem, > unsigned long ua, unsigned long *hpa); > +extern long mm_iommu_rm_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem, > + unsigned long ua, unsigned long *hpa); > extern long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem); > extern void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem); > #endif > diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_co= ntext_iommu.c > index da6a216..aa1565d 100644 > --- a/arch/powerpc/mm/mmu_context_iommu.c > +++ b/arch/powerpc/mm/mmu_context_iommu.c > @@ -63,12 +63,9 @@ static long mm_iommu_adjust_locked_vm(struct mm_struct= *mm, > return ret; > } > =20 > -bool mm_iommu_preregistered(void) > +bool mm_iommu_preregistered(mm_context_t *mm) > { > - if (!current || !current->mm) > - return false; > - > - return !list_empty(¤t->mm->context.iommu_group_mem_list); > + return !list_empty(&mm->iommu_group_mem_list); > } > EXPORT_SYMBOL_GPL(mm_iommu_preregistered); > =20 > @@ -231,6 +228,24 @@ unlock_exit: > } > EXPORT_SYMBOL_GPL(mm_iommu_put); > =20 > +struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(mm_context_t *mm, > + unsigned long ua, unsigned long size) > +{ > + struct mm_iommu_table_group_mem_t *mem, *ret =3D NULL; I think you could do with a comment here explaining why the lockless traversal is safe. > + list_for_each_entry_lockless(mem, &mm->iommu_group_mem_list, next) { > + if ((mem->ua <=3D ua) && > + (ua + size <=3D mem->ua + > + (mem->entries << PAGE_SHIFT))) { > + ret =3D mem; > + break; > + } > + } > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(mm_iommu_lookup_rm); > + > struct mm_iommu_table_group_mem_t *mm_iommu_lookup(unsigned long ua, > unsigned long size) > { > @@ -284,6 +299,26 @@ long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_= mem_t *mem, > } > EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa); > =20 > +long mm_iommu_rm_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem, > + unsigned long ua, unsigned long *hpa) > +{ > + const long entry =3D (ua - mem->ua) >> PAGE_SHIFT; > + void *va =3D &mem->hpas[entry]; > + unsigned long *ra; > + > + if (entry >=3D mem->entries) > + return -EFAULT; > + > + ra =3D (void *) vmalloc_to_phys(va); > + if (!ra) > + return -EFAULT; > + > + *hpa =3D *ra | (ua & ~PAGE_MASK); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(mm_iommu_rm_ua_to_hpa); > + > long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem) > { > if (atomic64_inc_not_zero(&mem->mapped)) --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --Tv3+oRj6D9L8lW+H Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJW3RIPAAoJEGw4ysog2bOStSsQAI+rrWq0m1b3h+LUedfjM7Gb plIuTYTBsMNp3fQf54ArNdiqnWs0A1zdO+eQMPp9NG8HmEKOLTsiPXKsWH76nToL zyt7+LNHWNVDAoih1HzHCFfxj/5LJuRbJ84h8mIZTdz+edg4GiilGDTKCviZkh5E RbUfGBiwOZdregxEJRvaVweDIUxbyZwCWSHCRudisVuGvmeHdEiLL6rBc3UWMh3f nAcbEORomj9JuUDeeBeQDcWJHSWe89YGiD4FGoMjYIl4M4sWm0P26U86DsjDCYxv tVCH9zPo/Lrdg0ht1YNCaFf8F/gVogTSOwdhBoEbF7tPMtX8iBaHKp6fP5cP27+n aCX0cQ9UVLxak9W1k1c6CHHDp7DSZo7s0o0zVvdI9knzPJJO2J6dOzweAE7jQ66R N9fsFg0kF4gJOKXGkXpmroKQSYXC6N7cgv9QuzM3xNztqKM6E2/KLbx/WktCKpqw R6zkSaX8zmy8icNDSxlh0W4hOlM0ciP2jkH8Qw+/1ClxTLjlQCTxVjoDUV4Wla8o ELmmdaDj0/PQvOguSInm1ItjXESljHrN9hFWBgmN4NEvCghYfBGVlIvzjIvZaBVD VmW/CGKqCsPwdgomU5rCw7xW5LSenkuiYntK64CzXru4/3cfnuvg2OL3/CHQ0OAj dS51CCjm43Ivp9EXnebV =TWB1 -----END PGP SIGNATURE----- --Tv3+oRj6D9L8lW+H--