From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Cc: David Rientjes <rientjes@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Kees Cook <keescook@chromium.org>, Will Drewry <wad@chromium.org>,
"Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
"Kleen, Andi" <andi.kleen@intel.com>,
Liran Alon <liran.alon@oracle.com>,
Mike Rapoport <rppt@kernel.org>,
x86@kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [RFCv2 13/16] KVM: Rework copy_to/from_guest() to avoid direct mapping
Date: Tue, 20 Oct 2020 09:18:56 +0300 [thread overview]
Message-ID: <20201020061859.18385-14-kirill.shutemov@linux.intel.com> (raw)
In-Reply-To: <20201020061859.18385-1-kirill.shutemov@linux.intel.com>
We are going unmap guest pages from direct mapping and cannot rely on it
for guest memory access. Use temporary kmap_atomic()-style mapping to
access guest memory.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
virt/kvm/kvm_main.c | 27 ++++++++++-
virt/lib/mem_protected.c | 101 +++++++++++++++++++++++++++++++++++++++
2 files changed, 126 insertions(+), 2 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4c008c7b4974..9b569b78874a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -51,6 +51,7 @@
#include <linux/io.h>
#include <linux/lockdep.h>
#include <linux/kthread.h>
+#include <linux/pagewalk.h>
#include <asm/processor.h>
#include <asm/ioctl.h>
@@ -154,6 +155,12 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm);
static unsigned long long kvm_createvm_count;
static unsigned long long kvm_active_vms;
+void *kvm_map_page_atomic(struct page *page);
+void kvm_unmap_page_atomic(void *vaddr);
+
+int kvm_init_protected_memory(void);
+void kvm_exit_protected_memory(void);
+
int __kvm_protect_memory(unsigned long start, unsigned long end, bool protect);
__weak void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,
@@ -2329,6 +2336,7 @@ int copy_from_guest(void *data, unsigned long hva, int len, bool protected)
int offset = offset_in_page(hva);
struct page *page;
int npages, seg;
+ void *vaddr;
if (!protected)
return __copy_from_user(data, (void __user *)hva, len);
@@ -2341,7 +2349,11 @@ int copy_from_guest(void *data, unsigned long hva, int len, bool protected)
npages = get_user_pages_unlocked(hva, 1, &page, FOLL_KVM);
if (npages != 1)
return -EFAULT;
- memcpy(data, page_address(page) + offset, seg);
+
+ vaddr = kvm_map_page_atomic(page);
+ memcpy(data, vaddr + offset, seg);
+ kvm_unmap_page_atomic(vaddr);
+
put_page(page);
len -= seg;
hva += seg;
@@ -2356,6 +2368,7 @@ int copy_to_guest(unsigned long hva, const void *data, int len, bool protected)
int offset = offset_in_page(hva);
struct page *page;
int npages, seg;
+ void *vaddr;
if (!protected)
return __copy_to_user((void __user *)hva, data, len);
@@ -2369,7 +2382,11 @@ int copy_to_guest(unsigned long hva, const void *data, int len, bool protected)
FOLL_WRITE | FOLL_KVM);
if (npages != 1)
return -EFAULT;
- memcpy(page_address(page) + offset, data, seg);
+
+ vaddr = kvm_map_page_atomic(page);
+ memcpy(vaddr + offset, data, seg);
+ kvm_unmap_page_atomic(vaddr);
+
put_page(page);
len -= seg;
hva += seg;
@@ -4945,6 +4962,10 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
if (r)
goto out_free;
+ if (IS_ENABLED(CONFIG_HAVE_KVM_PROTECTED_MEMORY) &&
+ kvm_init_protected_memory())
+ goto out_unreg;
+
kvm_chardev_ops.owner = module;
kvm_vm_fops.owner = module;
kvm_vcpu_fops.owner = module;
@@ -4968,6 +4989,7 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
return 0;
out_unreg:
+ kvm_exit_protected_memory();
kvm_async_pf_deinit();
out_free:
kmem_cache_destroy(kvm_vcpu_cache);
@@ -4989,6 +5011,7 @@ EXPORT_SYMBOL_GPL(kvm_init);
void kvm_exit(void)
{
+ kvm_exit_protected_memory();
debugfs_remove_recursive(kvm_debugfs_dir);
misc_deregister(&kvm_dev);
kmem_cache_destroy(kvm_vcpu_cache);
diff --git a/virt/lib/mem_protected.c b/virt/lib/mem_protected.c
index 0b01dd74f29c..1dfe82534242 100644
--- a/virt/lib/mem_protected.c
+++ b/virt/lib/mem_protected.c
@@ -5,6 +5,100 @@
#include <linux/vmalloc.h>
#include <asm/tlbflush.h>
+static pte_t **guest_map_ptes;
+static struct vm_struct *guest_map_area;
+
+void *kvm_map_page_atomic(struct page *page)
+{
+ pte_t *pte;
+ void *vaddr;
+
+ preempt_disable();
+ pte = guest_map_ptes[smp_processor_id()];
+ vaddr = guest_map_area->addr + smp_processor_id() * PAGE_SIZE;
+ set_pte(pte, mk_pte(page, PAGE_KERNEL));
+ return vaddr;
+}
+EXPORT_SYMBOL_GPL(kvm_map_page_atomic);
+
+void kvm_unmap_page_atomic(void *vaddr)
+{
+ pte_t *pte = guest_map_ptes[smp_processor_id()];
+ set_pte(pte, __pte(0));
+ flush_tlb_one_kernel((unsigned long)vaddr);
+ preempt_enable();
+}
+EXPORT_SYMBOL_GPL(kvm_unmap_page_atomic);
+
+int kvm_init_protected_memory(void)
+{
+ guest_map_ptes = kmalloc_array(num_possible_cpus(),
+ sizeof(pte_t *), GFP_KERNEL);
+ if (!guest_map_ptes)
+ return -ENOMEM;
+
+ guest_map_area = alloc_vm_area(PAGE_SIZE * num_possible_cpus(),
+ guest_map_ptes);
+ if (!guest_map_ptes) {
+ kfree(guest_map_ptes);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_init_protected_memory);
+
+void kvm_exit_protected_memory(void)
+{
+ if (guest_map_area)
+ free_vm_area(guest_map_area);
+ if (guest_map_ptes)
+ kfree(guest_map_ptes);
+}
+EXPORT_SYMBOL_GPL(kvm_exit_protected_memory);
+
+static int adjust_direct_mapping_pte_range(pmd_t *pmd, unsigned long addr,
+ unsigned long end,
+ struct mm_walk *walk)
+{
+ bool protect = (bool)walk->private;
+ pte_t *pte;
+ struct page *page;
+
+ if (pmd_trans_huge(*pmd)) {
+ page = pmd_page(*pmd);
+ if (is_huge_zero_page(page))
+ return 0;
+ VM_BUG_ON_PAGE(total_mapcount(page) != 1, page);
+ /* XXX: Would it fail with direct device assignment? */
+ VM_BUG_ON_PAGE(page_count(page) != 1, page);
+ kernel_map_pages(page, HPAGE_PMD_NR, !protect);
+ return 0;
+ }
+
+ pte = pte_offset_map(pmd, addr);
+ for (; addr != end; pte++, addr += PAGE_SIZE) {
+ pte_t entry = *pte;
+
+ if (!pte_present(entry))
+ continue;
+
+ if (is_zero_pfn(pte_pfn(entry)))
+ continue;
+
+ page = pte_page(entry);
+
+ VM_BUG_ON_PAGE(page_mapcount(page) != 1, page);
+ kernel_map_pages(page, 1, !protect);
+ }
+
+ return 0;
+}
+
+static const struct mm_walk_ops adjust_direct_mapping_ops = {
+ .pmd_entry = adjust_direct_mapping_pte_range,
+};
+
int __kvm_protect_memory(unsigned long start, unsigned long end, bool protect)
{
struct mm_struct *mm = current->mm;
@@ -50,6 +144,13 @@ int __kvm_protect_memory(unsigned long start, unsigned long end, bool protect)
if (ret)
goto out;
+ if (vma_is_anonymous(vma)) {
+ ret = walk_page_range_novma(mm, start, tmp,
+ &adjust_direct_mapping_ops, NULL,
+ (void *) protect);
+ if (ret)
+ goto out;
+ }
next:
start = tmp;
if (start < prev->vm_end)
--
2.26.2
next prev parent reply other threads:[~2020-10-20 6:19 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 6:18 [RFCv2 00/16] KVM protected memory extension Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 01/16] x86/mm: Move force_dma_unencrypted() to common code Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 02/16] x86/kvm: Introduce KVM memory protection feature Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 03/16] x86/kvm: Make DMA pages shared Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 04/16] x86/kvm: Use bounce buffers for KVM memory protection Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 05/16] x86/kvm: Make VirtIO use DMA API in KVM guest Kirill A. Shutemov
2020-10-20 8:06 ` Christoph Hellwig
2020-10-20 12:47 ` Kirill A. Shutemov
2020-10-22 3:31 ` Halil Pasic
2020-10-20 6:18 ` [RFCv2 06/16] x86/kvmclock: Share hvclock memory with the host Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 07/16] x86/realmode: Share trampoline area if KVM memory protection enabled Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 08/16] KVM: Use GUP instead of copy_from/to_user() to access guest memory Kirill A. Shutemov
2020-10-20 8:25 ` John Hubbard
2020-10-20 12:51 ` Kirill A. Shutemov
2020-10-22 11:49 ` Matthew Wilcox
2020-10-22 19:58 ` John Hubbard
2020-10-26 4:21 ` Matthew Wilcox
2020-10-26 4:44 ` John Hubbard
2020-10-26 13:28 ` Matthew Wilcox
2020-10-26 14:16 ` Jason Gunthorpe
2020-10-26 20:52 ` John Hubbard
2020-10-20 17:29 ` Ira Weiny
2020-10-22 11:37 ` Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 09/16] KVM: mm: Introduce VM_KVM_PROTECTED Kirill A. Shutemov
2020-10-21 18:47 ` Edgecombe, Rick P
2020-10-22 12:01 ` Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 10/16] KVM: x86: Use GUP for page walk instead of __get_user() Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 11/16] KVM: Protected memory extension Kirill A. Shutemov
2020-10-20 7:17 ` Peter Zijlstra
2020-10-20 12:55 ` Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 12/16] KVM: x86: Enabled protected " Kirill A. Shutemov
2020-10-20 6:18 ` Kirill A. Shutemov [this message]
2020-10-20 6:18 ` [RFCv2 14/16] KVM: Handle protected memory in __kvm_map_gfn()/__kvm_unmap_gfn() Kirill A. Shutemov
2020-10-21 18:50 ` Edgecombe, Rick P
2020-10-22 12:06 ` Kirill A. Shutemov
2020-10-22 16:59 ` Edgecombe, Rick P
2020-10-23 10:36 ` Kirill A. Shutemov
2020-10-22 3:26 ` Halil Pasic
2020-10-22 12:07 ` Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 15/16] KVM: Unmap protected pages from direct mapping Kirill A. Shutemov
2020-10-20 7:12 ` Peter Zijlstra
2020-10-20 12:18 ` David Hildenbrand
2020-10-20 13:20 ` David Hildenbrand
2020-10-21 1:20 ` Edgecombe, Rick P
2020-10-26 19:55 ` Tom Lendacky
2020-10-21 18:49 ` Edgecombe, Rick P
2020-10-23 12:37 ` Mike Rapoport
2020-10-23 16:32 ` Sean Christopherson
2020-10-20 6:18 ` [RFCv2 16/16] mm: Do not use zero page for VM_KVM_PROTECTED VMAs Kirill A. Shutemov
2020-10-20 7:46 ` [RFCv2 00/16] KVM protected memory extension Vitaly Kuznetsov
2020-10-20 13:49 ` Kirill A. Shutemov
2020-10-21 14:46 ` Vitaly Kuznetsov
2020-10-23 11:35 ` Kirill A. Shutemov
2020-10-23 12:01 ` Vitaly Kuznetsov
2020-10-21 18:20 ` Andy Lutomirski
2020-10-26 15:29 ` Kirill A. Shutemov
2020-10-26 23:58 ` Andy Lutomirski
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