From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
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>,
x86@kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
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>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Subject: Re: [RFC 06/16] KVM: Use GUP instead of copy_from/to_user() to access guest memory
Date: Mon, 25 May 2020 17:08:43 +0200 [thread overview]
Message-ID: <87a71w832c.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <20200522125214.31348-7-kirill.shutemov@linux.intel.com>
"Kirill A. Shutemov" <kirill@shutemov.name> writes:
> 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 | 78 ++++++++++++++++++++++++++++++++++------
> 2 files changed, 72 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 131cc1527d68..bd0bb600f610 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -503,6 +503,7 @@ struct kvm {
> struct srcu_struct srcu;
> struct srcu_struct irq_srcu;
> pid_t userspace_pid;
> + bool mem_protected;
> };
>
> #define kvm_err(fmt, ...) \
> @@ -727,6 +728,9 @@ 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);
> +int copy_to_guest(unsigned long hva, const void *data, int len);
> +
> 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 731c1e517716..033471f71dae 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2248,8 +2248,48 @@ static int next_segment(unsigned long len, int offset)
> return len;
> }
>
> +int copy_from_guest(void *data, unsigned long hva, int len)
> +{
> + int offset = offset_in_page(hva);
> + struct page *page;
> + int npages, seg;
> +
> + 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;
> + }
> +
> + return 0;
> +}
> +
> +int copy_to_guest(unsigned long hva, const void *data, int len)
> +{
> + int offset = offset_in_page(hva);
> + struct page *page;
> + int npages, seg;
> +
> + 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;
> + }
> + 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;
> @@ -2257,7 +2297,10 @@ static int __kvm_read_guest_page(struct kvm_memory_slot *slot, gfn_t gfn,
> 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 (protected)
> + r = copy_from_guest(data, addr + offset, len);
> + else
> + r = __copy_from_user(data, (void __user *)addr + offset, len);
> if (r)
> return -EFAULT;
> return 0;
> @@ -2268,7 +2311,8 @@ 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);
>
> @@ -2277,7 +2321,8 @@ 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);
Personally, I would've just added 'struct kvm' pointer to 'struct
kvm_memory_slot' to be able to extract 'mem_protected' info when
needed. This will make the patch much smaller.
> }
> EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest_page);
>
> @@ -2350,7 +2395,8 @@ 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;
> @@ -2358,7 +2404,11 @@ 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);
> +
> + if (protected)
> + r = copy_to_guest(addr + offset, data, len);
> + else
> + r = __copy_to_user((void __user *)addr + offset, data, len);
All users of copy_to_guest() will have to have the same 'if (protected)'
check, right? Why not move the check to copy_to/from_guest() then?
> if (r)
> return -EFAULT;
> mark_page_dirty_in_slot(memslot, gfn);
> @@ -2370,7 +2420,8 @@ 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);
>
> @@ -2379,7 +2430,8 @@ 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);
>
> @@ -2495,7 +2547,10 @@ 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);
> + if (kvm->mem_protected)
> + r = copy_to_guest(ghc->hva + offset, data, len);
> + else
> + r = __copy_to_user((void __user *)ghc->hva + offset, data, len);
> if (r)
> return -EFAULT;
> mark_page_dirty_in_slot(ghc->memslot, gpa >> PAGE_SHIFT);
> @@ -2530,7 +2585,10 @@ int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
> if (unlikely(!ghc->memslot))
> return kvm_read_guest(kvm, ghc->gpa, data, len);
>
> - r = __copy_from_user(data, (void __user *)ghc->hva, len);
> + if (kvm->mem_protected)
> + r = copy_from_guest(data, ghc->hva, len);
> + else
> + r = __copy_from_user(data, (void __user *)ghc->hva, len);
> if (r)
> return -EFAULT;
--
Vitaly
next prev parent reply other threads:[~2020-05-25 15:08 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 12:51 [RFC 00/16] KVM protected memory extension Kirill A. Shutemov
2020-05-22 12:51 ` [RFC 01/16] x86/mm: Move force_dma_unencrypted() to common code Kirill A. Shutemov
2020-05-22 12:52 ` [RFC 02/16] x86/kvm: Introduce KVM memory protection feature Kirill A. Shutemov
2020-05-25 14:58 ` Vitaly Kuznetsov
2020-05-25 15:15 ` Kirill A. Shutemov
2020-05-27 5:03 ` Sean Christopherson
2020-05-27 8:39 ` Vitaly Kuznetsov
2020-05-27 8:52 ` Sean Christopherson
2020-06-03 2:09 ` Huang, Kai
2020-06-03 11:14 ` Vitaly Kuznetsov
2020-05-22 12:52 ` [RFC 03/16] x86/kvm: Make DMA pages shared Kirill A. Shutemov
2020-05-22 12:52 ` [RFC 04/16] x86/kvm: Use bounce buffers for KVM memory protection Kirill A. Shutemov
2020-05-22 12:52 ` [RFC 05/16] x86/kvm: Make VirtIO use DMA API in KVM guest Kirill A. Shutemov
2020-05-22 12:52 ` [RFC 06/16] KVM: Use GUP instead of copy_from/to_user() to access guest memory Kirill A. Shutemov
2020-05-25 15:08 ` Vitaly Kuznetsov [this message]
2020-05-25 15:17 ` Kirill A. Shutemov
2020-06-01 16:35 ` Paolo Bonzini
2020-06-02 13:33 ` Kirill A. Shutemov
2020-05-26 6:14 ` Mike Rapoport
2020-05-26 21:56 ` Kirill A. Shutemov
2020-05-29 15:24 ` Kees Cook
2020-05-22 12:52 ` [RFC 07/16] KVM: mm: Introduce VM_KVM_PROTECTED Kirill A. Shutemov
2020-05-26 6:15 ` Mike Rapoport
2020-05-26 22:01 ` Kirill A. Shutemov
2020-05-26 6:40 ` John Hubbard
2020-05-26 22:04 ` Kirill A. Shutemov
2020-05-22 12:52 ` [RFC 08/16] KVM: x86: Use GUP for page walk instead of __get_user() Kirill A. Shutemov
2020-05-22 12:52 ` [RFC 09/16] KVM: Protected memory extension Kirill A. Shutemov
2020-05-25 15:26 ` Vitaly Kuznetsov
2020-05-25 15:34 ` Kirill A. Shutemov
2020-06-03 1:34 ` Huang, Kai
2020-05-22 12:52 ` [RFC 10/16] KVM: x86: Enabled protected " Kirill A. Shutemov
2020-05-25 15:26 ` Vitaly Kuznetsov
2020-05-26 6:16 ` Mike Rapoport
2020-05-26 21:58 ` Kirill A. Shutemov
2020-05-22 12:52 ` [RFC 11/16] KVM: Rework copy_to/from_guest() to avoid direct mapping Kirill A. Shutemov
2020-05-22 12:52 ` [RFC 12/16] x86/kvm: Share steal time page with host Kirill A. Shutemov
2020-05-22 12:52 ` [RFC 13/16] x86/kvmclock: Share hvclock memory with the host Kirill A. Shutemov
2020-05-25 15:22 ` Vitaly Kuznetsov
2020-05-25 15:25 ` Kirill A. Shutemov
2020-05-25 15:42 ` Vitaly Kuznetsov
2020-05-22 12:52 ` [RFC 14/16] KVM: Introduce gfn_to_pfn_memslot_protected() Kirill A. Shutemov
2020-05-22 12:52 ` [RFC 15/16] KVM: Handle protected memory in __kvm_map_gfn()/__kvm_unmap_gfn() Kirill A. Shutemov
2020-05-22 12:52 ` [RFC 16/16] KVM: Unmap protected pages from direct mapping Kirill A. Shutemov
2020-05-26 6:16 ` Mike Rapoport
2020-05-26 22:10 ` Kirill A. Shutemov
2020-05-25 5:27 ` [RFC 00/16] KVM protected memory extension Kirill A. Shutemov
2020-05-25 13:47 ` Liran Alon
2020-05-25 14:46 ` Kirill A. Shutemov
2020-05-25 15:56 ` Liran Alon
2020-05-26 6:17 ` Mike Rapoport
2020-05-26 10:16 ` Liran Alon
2020-05-26 11:38 ` Mike Rapoport
2020-05-27 15:45 ` Dave Hansen
2020-05-27 21:22 ` Mike Rapoport
2020-06-04 15:15 ` Marc Zyngier
2020-06-04 15:48 ` Sean Christopherson
2020-06-04 16:27 ` Marc Zyngier
2020-06-04 16:35 ` Will Deacon
2020-06-04 19:09 ` Nakajima, Jun
2020-06-04 21:03 ` Jim Mattson
2020-06-04 23:29 ` Nakajima, Jun
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