From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joel Schopp Subject: Re: [PATCH v4] arm64: fix VTTBR_BADDR_MASK Date: Tue, 19 Aug 2014 09:05:09 -0500 Message-ID: <53F35995.8010008@amd.com> References: <20140811203823.2828.36074.stgit@joelaarch64.amd.com> <20140812160521.GO10550@cbox> <53F26282.5010103@amd.com> <20140819122236.GB31086@cbox> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: , , , , Sungjinn Chung , Jungseok Lee To: Christoffer Dall Return-path: Received: from mail-bl2lp0212.outbound.protection.outlook.com ([207.46.163.212]:13897 "EHLO na01-bl2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752134AbaHSOH6 (ORCPT ); Tue, 19 Aug 2014 10:07:58 -0400 In-Reply-To: <20140819122236.GB31086@cbox> Sender: kvm-owner@vger.kernel.org List-ID: On 08/19/2014 07:22 AM, Christoffer Dall wrote: > On Mon, Aug 18, 2014 at 03:30:58PM -0500, Joel Schopp wrote: >> #endif /* __ARM_KVM_MMU_H__ */ >> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c >> index 16e7994..70f0f02 100644 >> --- a/arch/arm/kvm/mmu.c >> +++ b/arch/arm/kvm/mmu.c >> @@ -521,6 +521,7 @@ int create_hyp_io_mappings(void *from, void *to, phys_addr_t phys_addr) >> */ >> int kvm_alloc_stage2_pgd(struct kvm *kvm) >> { >> + unsigned int s2_pgds, s2_pgd_order; >> pgd_t *pgd; >> >> if (kvm->arch.pgd != NULL) { >> @@ -528,10 +529,18 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm) >> return -EINVAL; >> } >> >> - pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, S2_PGD_ORDER); >> + s2_pgds = (1 << (kvm_get_phys_addr_shift() - PGDIR_SHIFT)); >> + s2_pgd_order = get_order(s2_pgds * sizeof(pgd_t)); >> + >> + pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, s2_pgd_order); >> if (!pgd) >> return -ENOMEM; >> >> + if ((unsigned long)pgd & ~vttbr_baddr_mask) { >> + kvm_err("Stage-2 pgd not correctly aligned: %p\n", pgd); >> + return -EFAULT; >> + } >> >> >> There are two problems that I've found here. The first problem is that >> vttbr_baddr_mask isn't allocated yet at this point in the code. > allocated? you mean assigned? > aren't you setting vttbr_baddr_mask in kvm_arch_init()? that's > certainly called before kvm_arch_init_vm(). Yes, I mean assigned, at least I got the first letter correct :) All I know is that vttbr_baddr_mask was still zero and checking for zero and calling the set function gave it a value. > > >> The >> second problem is that pgd is a virtual address, ie pgd == >> 0xfffffe03bbb40000 while the vttbr masks off the high bits for a >> physical address, ie vttbr_baddr_mask=0x00007ffffffe0000 . Even >> correcting for those issues I haven't been able to make this check work >> properly. I'll resend v5 the patch with all the other suggested changes. >> > What are the issues that you face? Iow. what is the alignment of the > returned physical address? > > (You should be able to just to virt_to_phys(pgd) and use that to test > for the vttbr_baddr_mask). The addresses above are actually from my system, 64K page aligned on a 64K page kernel. I did use virt_to_phys() and the kernel got a null dereference and paniced, I didn't trace down where the panic was occuring. > > > Thanks, > -Christoffer