From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f70.google.com (mail-it0-f70.google.com [209.85.214.70]) by kanga.kvack.org (Postfix) with ESMTP id 58D646B02C3 for ; Thu, 8 Jun 2017 09:43:09 -0400 (EDT) Received: by mail-it0-f70.google.com with SMTP id a133so12247436itd.9 for ; Thu, 08 Jun 2017 06:43:09 -0700 (PDT) Received: from NAM01-SN1-obe.outbound.protection.outlook.com (mail-sn1nam01on0065.outbound.protection.outlook.com. [104.47.32.65]) by mx.google.com with ESMTPS id m128si5441732iof.91.2017.06.08.06.43.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 08 Jun 2017 06:43:08 -0700 (PDT) Subject: Re: [PATCH v6 10/34] x86, x86/mm, x86/xen, olpc: Use __va() against just the physical address in cr3 References: <20170607191309.28645.15241.stgit@tlendack-t1.amdoffice.net> <20170607191453.28645.92256.stgit@tlendack-t1.amdoffice.net> From: Tom Lendacky Message-ID: <4a7376fb-abfc-8edd-42b7-38de461ac65e@amd.com> Date: Thu, 8 Jun 2017 08:42:51 -0500 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Boris Ostrovsky , linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, iommu@lists.linux-foundation.org Cc: Rik van Riel , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Toshimitsu Kani , Arnd Bergmann , Jonathan Corbet , Matt Fleming , "Michael S. Tsirkin" , Joerg Roedel , Konrad Rzeszutek Wilk , Paolo Bonzini , Larry Woodman , Brijesh Singh , Ingo Molnar , Borislav Petkov , Andy Lutomirski , "H. Peter Anvin" , Andrey Ryabinin , Alexander Potapenko , Dave Young , Thomas Gleixner , Dmitry Vyukov , Juergen Gross , xen-devel On 6/7/2017 5:06 PM, Boris Ostrovsky wrote: > On 06/07/2017 03:14 PM, Tom Lendacky wrote: >> The cr3 register entry can contain the SME encryption bit that indicates >> the PGD is encrypted. The encryption bit should not be used when creating >> a virtual address for the PGD table. >> >> Create a new function, read_cr3_pa(), that will extract the physical >> address from the cr3 register. This function is then used where a virtual >> address of the PGD needs to be created/used from the cr3 register. >> >> Signed-off-by: Tom Lendacky >> --- >> arch/x86/include/asm/special_insns.h | 9 +++++++++ >> arch/x86/kernel/head64.c | 2 +- >> arch/x86/mm/fault.c | 10 +++++----- >> arch/x86/mm/ioremap.c | 2 +- >> arch/x86/platform/olpc/olpc-xo1-pm.c | 2 +- >> arch/x86/power/hibernate_64.c | 2 +- >> arch/x86/xen/mmu_pv.c | 6 +++--- >> 7 files changed, 21 insertions(+), 12 deletions(-) >> ... >> diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c >> index 1f386d7..2dc5243 100644 >> --- a/arch/x86/xen/mmu_pv.c >> +++ b/arch/x86/xen/mmu_pv.c >> @@ -2022,7 +2022,7 @@ static phys_addr_t __init xen_early_virt_to_phys(unsigned long vaddr) >> pmd_t pmd; >> pte_t pte; >> >> - pa = read_cr3(); >> + pa = read_cr3_pa(); >> pgd = native_make_pgd(xen_read_phys_ulong(pa + pgd_index(vaddr) * >> sizeof(pgd))); >> if (!pgd_present(pgd)) >> @@ -2102,7 +2102,7 @@ void __init xen_relocate_p2m(void) >> pt_phys = pmd_phys + PFN_PHYS(n_pmd); >> p2m_pfn = PFN_DOWN(pt_phys) + n_pt; >> >> - pgd = __va(read_cr3()); >> + pgd = __va(read_cr3_pa()); >> new_p2m = (unsigned long *)(2 * PGDIR_SIZE); >> idx_p4d = 0; >> save_pud = n_pud; >> @@ -2209,7 +2209,7 @@ static void __init xen_write_cr3_init(unsigned long cr3) >> { >> unsigned long pfn = PFN_DOWN(__pa(swapper_pg_dir)); >> >> - BUG_ON(read_cr3() != __pa(initial_page_table)); >> + BUG_ON(read_cr3_pa() != __pa(initial_page_table)); >> BUG_ON(cr3 != __pa(swapper_pg_dir)); >> >> /* > > > (Please copy Xen maintainers when modifying xen-related files.) Sorry about that, missed adding the Xen maintainers when I added this change. > > Given that page tables for Xen PV guests are controlled by the > hypervisor I don't think this change (although harmless) is necessary. I can back this change out if the Xen maintainers think that's best. > What may be needed is making sure X86_FEATURE_SME is not set for PV guests. And that may be something that Xen will need to control through either CPUID or MSR support for the PV guests. Thanks, Tom > > -boris > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org