From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754039Ab2HGJy1 (ORCPT ); Tue, 7 Aug 2012 05:54:27 -0400 Received: from e28smtp03.in.ibm.com ([122.248.162.3]:44041 "EHLO e28smtp03.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752316Ab2HGJy0 (ORCPT ); Tue, 7 Aug 2012 05:54:26 -0400 Message-ID: <5020E5BF.7070304@linux.vnet.ibm.com> Date: Tue, 07 Aug 2012 17:54:07 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120717 Thunderbird/14.0 MIME-Version: 1.0 To: Xiao Guangrong CC: Avi Kivity , Marcelo Tosatti , LKML , KVM Subject: [PATCH v5 10/12] KVM: introduce readonly memslot References: <5020E423.9080004@linux.vnet.ibm.com> In-Reply-To: <5020E423.9080004@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit x-cbid: 12080709-3864-0000-0000-00000413BCA6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In current code, if we map a readonly memory space from host to guest and the page is not currently mapped in the host, we will get a fault-pfn and async is not allowed, then the vm will crash We introduce readonly memory region to map ROM/ROMD to the guest, read access is happy for readonly memslot, write access on readonly memslot will cause KVM_EXIT_MMIO exit Signed-off-by: Xiao Guangrong --- Documentation/virtual/kvm/api.txt | 10 +++- arch/x86/include/asm/kvm.h | 1 + arch/x86/kvm/mmu.c | 9 ++++ arch/x86/kvm/x86.c | 1 + include/linux/kvm.h | 6 ++- virt/kvm/kvm_main.c | 81 +++++++++++++++++++++++++++++-------- 6 files changed, 87 insertions(+), 21 deletions(-) diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index bf33aaa..b91bfd4 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -857,7 +857,8 @@ struct kvm_userspace_memory_region { }; /* for kvm_memory_region::flags */ -#define KVM_MEM_LOG_DIRTY_PAGES 1UL +#define KVM_MEM_LOG_DIRTY_PAGES (1UL << 0) +#define KVM_MEM_READONLY (1UL << 1) This ioctl allows the user to create or modify a guest physical memory slot. When changing an existing slot, it may be moved in the guest @@ -873,9 +874,12 @@ It is recommended that the lower 21 bits of guest_phys_addr and userspace_addr be identical. This allows large pages in the guest to be backed by large pages in the host. -The flags field supports just one flag, KVM_MEM_LOG_DIRTY_PAGES, which +The flags field supports two flag, KVM_MEM_LOG_DIRTY_PAGES, which instructs kvm to keep track of writes to memory within the slot. See -the KVM_GET_DIRTY_LOG ioctl. +the KVM_GET_DIRTY_LOG ioctl. Another flag is KVM_MEM_READONLY when the +KVM_CAP_READONLY_MEM capability, it indicates the guest memory is read-only, +that means, guest is only allowed to read it. Writes will be posted to +userspace as KVM_EXIT_MMIO exits. When the KVM_CAP_SYNC_MMU capability, changes in the backing of the memory region are automatically reflected into the guest. For example, an mmap() diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h index 246617e..521bf25 100644 --- a/arch/x86/include/asm/kvm.h +++ b/arch/x86/include/asm/kvm.h @@ -25,6 +25,7 @@ #define __KVM_HAVE_DEBUGREGS #define __KVM_HAVE_XSAVE #define __KVM_HAVE_XCRS +#define __KVM_HAVE_READONLY_MEM /* Architectural interrupt line count. */ #define KVM_NR_INTERRUPTS 256 diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 5548971..8e312a2 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2647,6 +2647,15 @@ static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct * static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gfn_t gfn, pfn_t pfn) { + /* + * Do not cache the mmio info caused by writing the readonly gfn + * into the spte otherwise read access on readonly gfn also can + * caused mmio page fault and treat it as mmio access. + * Return 1 to tell kvm to emulate it. + */ + if (pfn == KVM_PFN_ERR_RO_FAULT) + return 1; + if (pfn == KVM_PFN_ERR_HWPOISON) { kvm_send_hwpoison_signal(gfn_to_hva(vcpu->kvm, gfn), current); return 0; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8ebf65c..4c86239 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2167,6 +2167,7 @@ int kvm_dev_ioctl_check_extension(long ext) case KVM_CAP_GET_TSC_KHZ: case KVM_CAP_PCI_2_3: case KVM_CAP_KVMCLOCK_CTRL: + case KVM_CAP_READONLY_MEM: r = 1; break; case KVM_CAP_COALESCED_MMIO: diff --git a/include/linux/kvm.h b/include/linux/kvm.h index dc3aa2a..94867d0 100644 --- a/include/linux/kvm.h +++ b/include/linux/kvm.h @@ -102,7 +102,8 @@ struct kvm_userspace_memory_region { }; /* for kvm_memory_region::flags */ -#define KVM_MEM_LOG_DIRTY_PAGES 1UL +#define KVM_MEM_LOG_DIRTY_PAGES (1UL << 0) +#define KVM_MEM_READONLY (1UL << 1) /* for KVM_IRQ_LINE */ struct kvm_irq_level { @@ -617,6 +618,9 @@ struct kvm_ppc_smmu_info { #define KVM_CAP_PPC_GET_SMMU_INFO 78 #define KVM_CAP_S390_COW 79 #define KVM_CAP_PPC_ALLOC_HTAB 80 +#ifdef __KVM_HAVE_READONLY_MEM +#define KVM_CAP_READONLY_MEM 81 +#endif #ifdef KVM_CAP_IRQ_ROUTING diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1bd83a6..5e899d9 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -680,7 +680,13 @@ void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new) static int check_memory_region_flags(struct kvm_userspace_memory_region *mem) { - if (mem->flags & ~KVM_MEM_LOG_DIRTY_PAGES) + u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES; + +#ifdef KVM_CAP_READONLY_MEM + valid_flags |= KVM_MEM_READONLY; +#endif + + if (mem->flags & ~valid_flags) return -EINVAL; return 0; @@ -973,18 +979,32 @@ out: return size; } -static unsigned long gfn_to_hva_many(struct kvm_memory_slot *slot, gfn_t gfn, - gfn_t *nr_pages) +static bool memslot_is_readonly(struct kvm_memory_slot *slot) +{ + return slot->flags & KVM_MEM_READONLY; +} + +static unsigned long __gfn_to_hva_many(struct kvm_memory_slot *slot, gfn_t gfn, + gfn_t *nr_pages, bool write) { if (!slot || slot->flags & KVM_MEMSLOT_INVALID) return KVM_HVA_ERR_BAD; + if (memslot_is_readonly(slot) && write) + return KVM_HVA_ERR_RO_BAD; + if (nr_pages) *nr_pages = slot->npages - (gfn - slot->base_gfn); return gfn_to_hva_memslot(slot, gfn); } +static unsigned long gfn_to_hva_many(struct kvm_memory_slot *slot, gfn_t gfn, + gfn_t *nr_pages) +{ + return __gfn_to_hva_many(slot, gfn, nr_pages, true); +} + unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn) { return gfn_to_hva_many(gfn_to_memslot(kvm, gfn), gfn, NULL); @@ -997,7 +1017,7 @@ EXPORT_SYMBOL_GPL(gfn_to_hva); */ static unsigned long gfn_to_hva_read(struct kvm *kvm, gfn_t gfn) { - return gfn_to_hva_many(gfn_to_memslot(kvm, gfn), gfn, NULL); + return __gfn_to_hva_many(gfn_to_memslot(kvm, gfn), gfn, NULL, false); } static int kvm_read_hva(void *data, void __user *hva, int len) @@ -1108,6 +1128,17 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault, return npages; } +static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault) +{ + if (unlikely(!(vma->vm_flags & VM_READ))) + return false; + + if (write_fault && (unlikely(!(vma->vm_flags & VM_WRITE)))) + return false; + + return true; +} + /* * Pin guest page in memory and return its pfn. * @addr: host virtual address which maps memory to the guest @@ -1132,8 +1163,6 @@ static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, /* we can do it either atomically or asynchronously, not both */ BUG_ON(atomic && async); - BUG_ON(!write_fault && !writable); - if (hva_to_pfn_fast(addr, atomic, async, write_fault, writable, &pfn)) return pfn; @@ -1160,7 +1189,7 @@ static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, vma->vm_pgoff; BUG_ON(!kvm_is_mmio_pfn(pfn)); } else { - if (async && (vma->vm_flags & VM_WRITE)) + if (async && vma_is_valid(vma, write_fault)) *async = true; pfn = KVM_PFN_ERR_FAULT; } @@ -1169,19 +1198,40 @@ exit: return pfn; } +static pfn_t +__gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn, bool atomic, + bool *async, bool write_fault, bool *writable) +{ + unsigned long addr = __gfn_to_hva_many(slot, gfn, NULL, write_fault); + + if (addr == KVM_HVA_ERR_RO_BAD) + return KVM_PFN_ERR_RO_FAULT; + + if (kvm_is_error_hva(addr)) + return KVM_PFN_ERR_BAD; + + /* Do not map writable pfn in the readonly memslot. */ + if (writable && memslot_is_readonly(slot)) { + *writable = false; + writable = NULL; + } + + return hva_to_pfn(addr, atomic, async, write_fault, + writable); +} + static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic, bool *async, bool write_fault, bool *writable) { - unsigned long addr; + struct kvm_memory_slot *slot; if (async) *async = false; - addr = gfn_to_hva(kvm, gfn); - if (kvm_is_error_hva(addr)) - return KVM_PFN_ERR_BAD; + slot = gfn_to_memslot(kvm, gfn); - return hva_to_pfn(addr, atomic, async, write_fault, writable); + return __gfn_to_pfn_memslot(slot, gfn, atomic, async, write_fault, + writable); } pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn) @@ -1212,15 +1262,12 @@ EXPORT_SYMBOL_GPL(gfn_to_pfn_prot); pfn_t gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn) { - unsigned long addr = gfn_to_hva_memslot(slot, gfn); - return hva_to_pfn(addr, false, NULL, true, NULL); + return __gfn_to_pfn_memslot(slot, gfn, false, NULL, true, NULL); } pfn_t gfn_to_pfn_memslot_atomic(struct kvm_memory_slot *slot, gfn_t gfn) { - unsigned long addr = gfn_to_hva_memslot(slot, gfn); - - return hva_to_pfn(addr, true, NULL, true, NULL); + return __gfn_to_pfn_memslot(slot, gfn, true, NULL, true, NULL); } EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot_atomic); -- 1.7.7.6