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Thu, 14 Feb 2019 16:56:28 GMT Received: from [192.168.1.16] (/24.9.64.241) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 14 Feb 2019 08:56:27 -0800 Subject: Re: [RFC PATCH v8 04/14] swiotlb: Map the buffer if it was unmapped by XPFO To: Christoph Hellwig Cc: juergh@gmail.com, tycho@tycho.ws, jsteckli@amazon.de, ak@linux.intel.com, torvalds@linux-foundation.org, liran.alon@oracle.com, keescook@google.com, akpm@linux-foundation.org, mhocko@suse.com, catalin.marinas@arm.com, will.deacon@arm.com, jmorris@namei.org, konrad.wilk@oracle.com, Juerg Haefliger , deepa.srinivasan@oracle.com, chris.hyser@oracle.com, tyhicks@canonical.com, dwmw@amazon.co.uk, andrew.cooper3@citrix.com, jcm@redhat.com, boris.ostrovsky@oracle.com, kanth.ghatraju@oracle.com, oao.m.martins@oracle.com, jmattson@google.com, pradeep.vincent@oracle.com, john.haxby@oracle.com, tglx@linutronix.de, kirill.shutemov@linux.intel.com, steven.sistare@oracle.com, labbott@redhat.com, luto@kernel.org, dave.hansen@intel.com, peterz@infradead.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Tycho Andersen References: <20190214074747.GA10666@lst.de> From: Khalid Aziz Organization: Oracle Corp Message-ID: <3c75c46c-2a5a-cd75-83d4-f77d96d22f7d@oracle.com> Date: Thu, 14 Feb 2019 09:56:24 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190214074747.GA10666@lst.de> Content-Type: multipart/mixed; boundary="------------4E8F634EF1C80F4AD05A0F4B" Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9167 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=706 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902140114 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: This is a multi-part message in MIME format. --------------4E8F634EF1C80F4AD05A0F4B Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 2/14/19 12:47 AM, Christoph Hellwig wrote: > On Wed, Feb 13, 2019 at 05:01:27PM -0700, Khalid Aziz wrote: >> +++ b/kernel/dma/swiotlb.c >> @@ -396,8 +396,9 @@ static void swiotlb_bounce(phys_addr_t orig_addr, = phys_addr_t tlb_addr, >> { >> unsigned long pfn =3D PFN_DOWN(orig_addr); >> unsigned char *vaddr =3D phys_to_virt(tlb_addr); >> + struct page *page =3D pfn_to_page(pfn); >> =20 >> - if (PageHighMem(pfn_to_page(pfn))) { >> + if (PageHighMem(page) || xpfo_page_is_unmapped(page)) { >=20 > I think this just wants a page_unmapped or similar helper instead of > needing the xpfo_page_is_unmapped check. We actually have quite > a few similar construct in the arch dma mapping code for architectures > that require cache flushing. As I am not the original author of this patch, I am interpreting the original intent. I think xpfo_page_is_unmapped() was added to account for kernel build without CONFIG_XPFO. xpfo_page_is_unmapped() has an alternate definition to return false if CONFIG_XPFO is not defined. xpfo_is_unmapped() is cleaned up further in patch 11 ("xpfo, mm: remove dependency on CONFIG_PAGE_EXTENSION") to a one-liner "return PageXpfoUnmapped(page);". xpfo_is_unmapped() can be eliminated entirely by adding an else clause to the following code added by that patch: --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -398,6 +402,15 @@ TESTCLEARFLAG(Young, young, PF_ANY) PAGEFLAG(Idle, idle, PF_ANY) #endif +#ifdef CONFIG_XPFO +PAGEFLAG(XpfoUser, xpfo_user, PF_ANY) +TESTCLEARFLAG(XpfoUser, xpfo_user, PF_ANY) +TESTSETFLAG(XpfoUser, xpfo_user, PF_ANY) +PAGEFLAG(XpfoUnmapped, xpfo_unmapped, PF_ANY) +TESTCLEARFLAG(XpfoUnmapped, xpfo_unmapped, PF_ANY) +TESTSETFLAG(XpfoUnmapped, xpfo_unmapped, PF_ANY) +#endif + /* * On an anonymous page mapped into a user virtual memory area, * page->mapping points to its anon_vma, not to a struct address_space; Adding the following #else to above conditional: #else TESTPAGEFLAG_FALSE(XpfoUser) TESTPAGEFLAG_FALSE(XpfoUnmapped) should allow us to eliminate xpfo_is_unmapped(). Right? Thanks, Khalid >=20 >> +bool xpfo_page_is_unmapped(struct page *page) >> +{ >> + struct xpfo *xpfo; >> + >> + if (!static_branch_unlikely(&xpfo_inited)) >> + return false; >> + >> + xpfo =3D lookup_xpfo(page); >> + if (unlikely(!xpfo) && !xpfo->inited) >> + return false; >> + >> + return test_bit(XPFO_PAGE_UNMAPPED, &xpfo->flags); >> +} >> +EXPORT_SYMBOL(xpfo_page_is_unmapped); >=20 > And at least for swiotlb there is no need to export this helper, > as it is always built in. >=20 --------------4E8F634EF1C80F4AD05A0F4B Content-Type: application/pgp-keys; name="pEpkey.asc" Content-Transfer-Encoding: quoted-printable Content-Disposition: attachment; filename="pEpkey.asc" -----BEGIN PGP PUBLIC KEY BLOCK----- mQGNBFwdSxMBDACs4wtsihnZ9TVeZBZYPzcj1sl7hz41PYvHKAq8FfBOl4yC6ghp U0FDo3h8R7ze0VGU6n5b+M6fbKvOpIYT1r02cfWsKVtcssCyNhkeeL5A5X9z5vgt QnDDhnDdNQr4GmJVwA9XPvB/Pa4wOMGz9TbepWfhsyPtWsDXjvjFLVScOorPddrL /lFhriUssPrlffmNOMKdxhqGu6saUZN2QBoYjiQnUimfUbM6rs2dcSX4SVeNwl9B 2LfyF3kRxmjk964WCrIp0A2mB7UUOizSvhr5LqzHCXyP0HLgwfRd3s6KNqb2etes FU3bINxNpYvwLCy0xOw4DYcerEyS1AasrTgh2jr3T4wtPcUXBKyObJWxr5sWx3sz /DpkJ9jupI5ZBw7rzbUfoSV3wNc5KBZhmqjSrc8G1mDHcx/B4Rv47LsdihbWkeeB PVzB9QbNqS1tjzuyEAaRpfmYrmGM2/9HNz0p2cOTsk2iXSaObx/EbOZuhAMYu4zH y744QoC+Wf08N5UAEQEAAbQkS2hhbGlkIEF6aXogPGtoYWxpZC5heml6QG9yYWNs ZS5jb20+iQHUBBMBCAA+FiEErS+7JMqGyVyRyPqp4t2wFa8wz0MFAlwdSxQCGwMF CQHhM4AFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AACgkQ4t2wFa8wz0PaZwv/b55t AIoG8+KHig+IwVqXwWTpolhs+19mauBqRAK+/vPU6wvmrzJ1cz9FTgrmQf0GAPOI YZvSpH8Z563kAGRxCi9LKX1vM8TA60+0oazWIP8epLudAsQ3xbFFedc0LLoyWCGN u/VikES6QIn+2XaSKaYfXC/qhiXYJ0fOOXnXWv/t2eHtaGC1H+/kYEG5rFtLnILL fyFnxO3wf0r4FtLrvxftb6U0YCe4DSAed+27HqpLeaLCVpv/U+XOfe4/Loo1yIpm KZwiXvc0G2UUK19mNjp5AgDKJHwZHn3tS/1IV/mFtDT9YkKEzNs4jYkA5FzDMwB7 RD5l/EVf4tXPk4/xmc4Rw7eB3X8z8VGw5V8kDZ5I8xGIxkLpgzh56Fg420H54a7m 714aI0ruDWfVyC0pACcURTsMLAl4aN6E0v8rAUQ1vCLVobjNhLmfyJEwLUDqkwph rDUagtEwWgIzekcyPW8UaalyS1gG7uKNutZpe/c9Vr5Djxo2PzM7+dmSMB81uQGN BFwdSxMBDAC8uFhUTc5o/m49LCBTYSX79415K1EluskQkIAzGrtLgE/8DHrt8rtQ FSum+RYcA1L2aIS2eIw7M9Nut9IOR7YDGDDP+lcEJLa6L2LQpRtO65IHKqDQ1TB9 la4qi+QqS8WFo9DLaisOJS0jS6kO6ySYF0zRikje/hlsfKwxfq/RvZiKlkazRWjx RBnGhm+niiRD5jOJEAeckbNBhg+6QIizLo+g4xTnmAhxYR8eye2kG1tX1VbIYRX1 3SrdObgEKj5JGUGVRQnf/BM4pqYAy9szEeRcVB9ZXuHmy2mILaX3pbhQF2MssYE1 KjYhT+/U3RHfNZQq5sUMDpU/VntCd2fN6FGHNY0SHbMAMK7CZamwlvJQC0WzYFa+ jq1t9ei4P/HC8yLkYWpJW2yuxTpD8QP9yZ6zY+htiNx1mrlf95epwQOy/9oS86Dn MYWnX9VP8gSuiESUSx87gD6UeftGkBjoG2eX9jcwZOSu1YMhKxTBn8tgGH3LqR5U QLSSR1ozTC0AEQEAAYkBvAQYAQgAJhYhBK0vuyTKhslckcj6qeLdsBWvMM9DBQJc HUsTAhsMBQkB4TOAAAoJEOLdsBWvMM9D8YsL/0rMCewC6L15TTwer6GzVpRwbTuP rLtTcDumy90jkJfaKVUnbjvoYFAcRKceTUP8rz4seM/R1ai78BS78fx4j3j9qeWH rX3C0k2aviqjaF0zQ86KEx6xhdHWYPjmtpt3DwSYcV4Gqefh31Ryl5zO5FIz5yQy Z+lHCH+oBD51LMxrgobUmKmT3NOhbAIcYnOHEqsWyGrXD9qi0oj1Cos/t6B2oFaY IrLdMkklt+aJYV4wu3gWRW/HXypgeo0uDWOowfZSVi/u5lkn9WMUUOjIeL1IGJ7x U4JTAvt+f0BbX6b1BIC0nygMgdVe3tgKPIlniQc24Cj8pW8D8v+K7bVuNxxmdhT4 71XsoNYYmmB96Z3g6u2s9MY9h/0nC7FI6XSk/z584lGzzlwzPRpTOxW7fi/E/38o E6wtYze9oihz8mbNHY3jtUGajTsv/F7Jl42rmnbeukwfN2H/4gTDV1sB/D8z5G1+ +Wrj8Rwom6h21PXZRKnlkis7ibQfE+TxqOI7vg=3D=3D =3DnPqY -----END PGP PUBLIC KEY BLOCK----- --------------4E8F634EF1C80F4AD05A0F4B--