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Peter Anvin" , Dan Williams , Paolo Bonzini , Jane Chu , "Aneesh Kumar K . V" , Sean Christopherson , Tianyu Lan , Mike Rapoport , Rick Edgecombe , linux-mm@kvack.org, Borislav Petkov , x86@kernel.org Subject: Re: [RFC 1/2] x86/mm/cpa: always fail when user address is passed Message-ID: References: <20220614063933.13030-1-42.hyeyoo@gmail.com> <20220614063933.13030-2-42.hyeyoo@gmail.com> <660a5c93-e8cb-1c2f-5b27-c5e341de0bcd@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <660a5c93-e8cb-1c2f-5b27-c5e341de0bcd@intel.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655369397; a=rsa-sha256; cv=none; b=GVGIQPGxgH+EKPAXJS5tBmj8B/aq9QkCZ70B+8xpRZWIevPZo2pJ9pT+n4E5JIxJmAF41G 6yxkUJfS0XMOkMMn31Lan26Gu8cWt+LIXaWCcQI+Lp5UCqBgib7yNfWOtg2eUb4foORZ7W afl9luQ9U08jM7g3WkIMMNnFjc/GkvA= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=Xs0H00bS; spf=pass (imf13.hostedemail.com: domain of 42.hyeyoo@gmail.com designates 209.85.214.173 as permitted sender) smtp.mailfrom=42.hyeyoo@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655369397; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=kJDbvowK7n9hVfAhRNHK7TUojzQKsLHUXYMx1c1kPK4=; b=GnIV1kFIQDhrG9PG6EulCDEUQidDHznAnWjr3Gbn93x0mrpQ32ftshHCOf3lt3hwf++7Ss yi7ZrL9+QTaYqdkIdWh++2hqOq4DaTcx7LBN2xpt+Ua5PCZhfZQhu9fz/kXsz5tYZrwGfN +TAVBMAf0MWOMyyL4HqTnZo1MvbbR1E= X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 2C63720088 X-Stat-Signature: qaokcjojocmkzpxaqskdtiwc9tqeoaap Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=Xs0H00bS; spf=pass (imf13.hostedemail.com: domain of 42.hyeyoo@gmail.com designates 209.85.214.173 as permitted sender) smtp.mailfrom=42.hyeyoo@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-HE-Tag: 1655369396-153538 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: On Tue, Jun 14, 2022 at 11:31:48AM -0700, Dave Hansen wrote: > On 6/13/22 23:39, Hyeonggon Yoo wrote: > > @@ -1514,6 +1515,11 @@ static int __change_page_attr(struct cpa_data *cpa, int primary) > > pte_t *kpte, old_pte; > > > > address = __cpa_addr(cpa, cpa->curpage); > > + > > + if (WARN((IS_ENABLED(CONFIG_EFI) ? cpa->pgd != efi_mm.pgd : true) > > + && address <= TASK_SIZE_MAX, > > + KERN_WARNING "CPA: Got a user address")) > > + return -EINVAL; > > I was expecting this to actually go after _PAGE_USER, not necessarily > userspace addresses themselves. userspace ptes may not have _PAGE_USER set. (e.g. swap entry) I think it's more accurate to go after user addresses. > What does and should happen with the VDSO, for instance? It's a > _PAGE_USER mapping, but it's >TASK_SIZE. you mean vsyscall? AFAIK address of mapped vDSO image is < TASK_SIZE. (or please tell me I'm wrong) > Should set_page_attr() work on it? vsyscall does not need CPA functionalities. So I don't think it (__change_page_attr()) should work on vsyscall. I think renaming fault_in_kernel_space() and using it would be more robust than simply using the expression (address <= TASK_SIZE_MAX). -- Thanks, Hyeonggon