From: Ira Weiny <ira.weiny@intel.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: 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>,
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: Re: [RFCv2 08/16] KVM: Use GUP instead of copy_from/to_user() to access guest memory
Date: Tue, 20 Oct 2020 10:29:44 -0700 [thread overview]
Message-ID: <20201020172944.GA165907@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20201020061859.18385-9-kirill.shutemov@linux.intel.com>
On Tue, Oct 20, 2020 at 09:18:51AM +0300, Kirill A. Shutemov wrote:
> New helpers copy_from_guest()/copy_to_guest() to be used if KVM memory
> protection feature is enabled.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> ---
> include/linux/kvm_host.h | 4 ++
> virt/kvm/kvm_main.c | 90 +++++++++++++++++++++++++++++++---------
> 2 files changed, 75 insertions(+), 19 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 05e3c2fb3ef7..380a64613880 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -504,6 +504,7 @@ struct kvm {
> struct srcu_struct irq_srcu;
> pid_t userspace_pid;
> unsigned int max_halt_poll_ns;
> + bool mem_protected;
> };
>
> #define kvm_err(fmt, ...) \
> @@ -728,6 +729,9 @@ void kvm_set_pfn_dirty(kvm_pfn_t pfn);
> void kvm_set_pfn_accessed(kvm_pfn_t pfn);
> void kvm_get_pfn(kvm_pfn_t pfn);
>
> +int copy_from_guest(void *data, unsigned long hva, int len, bool protected);
> +int copy_to_guest(unsigned long hva, const void *data, int len, bool protected);
> +
> void kvm_release_pfn(kvm_pfn_t pfn, bool dirty, struct gfn_to_pfn_cache *cache);
> int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
> int len);
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index cf88233b819a..a9884cb8c867 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2313,19 +2313,70 @@ static int next_segment(unsigned long len, int offset)
> return len;
> }
>
> +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;
> +
> + if (!protected)
> + return __copy_from_user(data, (void __user *)hva, len);
> +
> + might_fault();
> + kasan_check_write(data, len);
> + check_object_size(data, len, false);
> +
> + while ((seg = next_segment(len, offset)) != 0) {
> + npages = get_user_pages_unlocked(hva, 1, &page, 0);
> + if (npages != 1)
> + return -EFAULT;
> + memcpy(data, page_address(page) + offset, seg);
> + put_page(page);
> + len -= seg;
> + hva += seg;
> + offset = 0;
Why is data not updated on each iteration?
> + }
> +
> + return 0;
> +}
> +
> +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;
> +
> + if (!protected)
> + return __copy_to_user((void __user *)hva, data, len);
> +
> + might_fault();
> + kasan_check_read(data, len);
> + check_object_size(data, len, true);
> +
> + while ((seg = next_segment(len, offset)) != 0) {
> + npages = get_user_pages_unlocked(hva, 1, &page, FOLL_WRITE);
> + if (npages != 1)
> + return -EFAULT;
> + memcpy(page_address(page) + offset, data, seg);
> + put_page(page);
> + len -= seg;
> + hva += seg;
> + offset = 0;
Same question? Doesn't this result in *data being copied to multiple pages?
Ira
> + }
> +
> + return 0;
> +}
> +
> static int __kvm_read_guest_page(struct kvm_memory_slot *slot, gfn_t gfn,
> - void *data, int offset, int len)
> + void *data, int offset, int len,
> + bool protected)
> {
> - int r;
> unsigned long addr;
>
> addr = gfn_to_hva_memslot_prot(slot, gfn, NULL);
> if (kvm_is_error_hva(addr))
> return -EFAULT;
> - r = __copy_from_user(data, (void __user *)addr + offset, len);
> - if (r)
> - return -EFAULT;
> - return 0;
> + return copy_from_guest(data, addr + offset, len, protected);
> }
>
> int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
> @@ -2333,7 +2384,8 @@ int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
> {
> struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
>
> - return __kvm_read_guest_page(slot, gfn, data, offset, len);
> + return __kvm_read_guest_page(slot, gfn, data, offset, len,
> + kvm->mem_protected);
> }
> EXPORT_SYMBOL_GPL(kvm_read_guest_page);
>
> @@ -2342,7 +2394,8 @@ int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data,
> {
> struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
>
> - return __kvm_read_guest_page(slot, gfn, data, offset, len);
> + return __kvm_read_guest_page(slot, gfn, data, offset, len,
> + vcpu->kvm->mem_protected);
> }
> EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest_page);
>
> @@ -2415,7 +2468,8 @@ int kvm_vcpu_read_guest_atomic(struct kvm_vcpu *vcpu, gpa_t gpa,
> EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest_atomic);
>
> static int __kvm_write_guest_page(struct kvm_memory_slot *memslot, gfn_t gfn,
> - const void *data, int offset, int len)
> + const void *data, int offset, int len,
> + bool protected)
> {
> int r;
> unsigned long addr;
> @@ -2423,7 +2477,8 @@ static int __kvm_write_guest_page(struct kvm_memory_slot *memslot, gfn_t gfn,
> addr = gfn_to_hva_memslot(memslot, gfn);
> if (kvm_is_error_hva(addr))
> return -EFAULT;
> - r = __copy_to_user((void __user *)addr + offset, data, len);
> +
> + r = copy_to_guest(addr + offset, data, len, protected);
> if (r)
> return -EFAULT;
> mark_page_dirty_in_slot(memslot, gfn);
> @@ -2435,7 +2490,8 @@ int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn,
> {
> struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
>
> - return __kvm_write_guest_page(slot, gfn, data, offset, len);
> + return __kvm_write_guest_page(slot, gfn, data, offset, len,
> + kvm->mem_protected);
> }
> EXPORT_SYMBOL_GPL(kvm_write_guest_page);
>
> @@ -2444,7 +2500,8 @@ int kvm_vcpu_write_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn,
> {
> struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
>
> - return __kvm_write_guest_page(slot, gfn, data, offset, len);
> + return __kvm_write_guest_page(slot, gfn, data, offset, len,
> + vcpu->kvm->mem_protected);
> }
> EXPORT_SYMBOL_GPL(kvm_vcpu_write_guest_page);
>
> @@ -2560,7 +2617,7 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> if (unlikely(!ghc->memslot))
> return kvm_write_guest(kvm, gpa, data, len);
>
> - r = __copy_to_user((void __user *)ghc->hva + offset, data, len);
> + r = copy_to_guest(ghc->hva + offset, data, len, kvm->mem_protected);
> if (r)
> return -EFAULT;
> mark_page_dirty_in_slot(ghc->memslot, gpa >> PAGE_SHIFT);
> @@ -2581,7 +2638,6 @@ int kvm_read_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> unsigned long len)
> {
> struct kvm_memslots *slots = kvm_memslots(kvm);
> - int r;
> gpa_t gpa = ghc->gpa + offset;
>
> BUG_ON(len + offset > ghc->len);
> @@ -2597,11 +2653,7 @@ int kvm_read_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> if (unlikely(!ghc->memslot))
> return kvm_read_guest(kvm, gpa, data, len);
>
> - r = __copy_from_user(data, (void __user *)ghc->hva + offset, len);
> - if (r)
> - return -EFAULT;
> -
> - return 0;
> + return copy_from_guest(data, ghc->hva + offset, len, kvm->mem_protected);
> }
> EXPORT_SYMBOL_GPL(kvm_read_guest_offset_cached);
>
> --
> 2.26.2
>
>
next prev parent reply other threads:[~2020-10-20 17:29 UTC|newest]
Thread overview: 83+ 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 ` 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 ` 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 ` 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 ` 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 ` Kirill A. Shutemov
2020-10-20 7:46 ` kernel test robot
2020-10-20 8:48 ` kernel test robot
2020-10-20 6:18 ` [RFCv2 05/16] x86/kvm: Make VirtIO use DMA API in KVM guest Kirill A. Shutemov
2020-10-20 6:18 ` Kirill A. Shutemov
2020-10-20 8:06 ` Christoph Hellwig
2020-10-20 12:47 ` Kirill A. Shutemov
2020-10-20 9:18 ` kernel test robot
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 ` 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 ` 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 6:18 ` 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 [this message]
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
2020-10-20 6:18 ` 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 ` Kirill A. Shutemov
2020-10-20 6:18 ` [RFCv2 11/16] KVM: Protected memory extension Kirill A. Shutemov
2020-10-20 6:18 ` 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
2020-10-20 9:01 ` kernel test robot
2020-10-20 6:18 ` [RFCv2 13/16] KVM: Rework copy_to/from_guest() to avoid direct mapping Kirill A. Shutemov
2020-10-20 6:18 ` Kirill A. Shutemov
2020-10-20 9:40 ` kernel test robot
2020-10-20 6:18 ` [RFCv2 14/16] KVM: Handle protected memory in __kvm_map_gfn()/__kvm_unmap_gfn() Kirill A. Shutemov
2020-10-20 6:18 ` Kirill A. Shutemov
2020-10-20 10:34 ` kernel test robot
2020-10-20 11:56 ` kernel test robot
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 6:18 ` 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 6:18 ` 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
2020-10-21 18:20 ` Andy Lutomirski
2020-10-26 15:29 ` Kirill A. Shutemov
2020-10-26 23:58 ` Andy Lutomirski
2020-10-26 23:58 ` Andy Lutomirski
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