From: Mike Rapoport <rppt@kernel.org>
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>,
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: [RFC 07/16] KVM: mm: Introduce VM_KVM_PROTECTED
Date: Tue, 26 May 2020 09:15:52 +0300 [thread overview]
Message-ID: <20200526061552.GD13247@kernel.org> (raw)
In-Reply-To: <20200522125214.31348-8-kirill.shutemov@linux.intel.com>
On Fri, May 22, 2020 at 03:52:05PM +0300, Kirill A. Shutemov wrote:
> The new VMA flag that indicate a VMA that is not accessible to userspace
> but usable by kernel with GUP if FOLL_KVM is specified.
>
> The FOLL_KVM is only used in the KVM code. The code has to know how to
> deal with such pages.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> ---
> include/linux/mm.h | 8 ++++++++
> mm/gup.c | 20 ++++++++++++++++----
> mm/huge_memory.c | 20 ++++++++++++++++----
> mm/memory.c | 3 +++
> mm/mmap.c | 3 +++
> virt/kvm/async_pf.c | 4 ++--
> virt/kvm/kvm_main.c | 9 +++++----
> 7 files changed, 53 insertions(+), 14 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index e1882eec1752..4f7195365cc0 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -329,6 +329,8 @@ extern unsigned int kobjsize(const void *objp);
> # define VM_MAPPED_COPY VM_ARCH_1 /* T if mapped copy of data (nommu mmap) */
> #endif
>
> +#define VM_KVM_PROTECTED 0
With all the ideas about removing pages from the direct mapi floating
around I wouldn't limit this to KVM.
VM_NOT_IN_DIRECT_MAP would describe such areas better, but I realise
it's very far from perfect and nothing better does not comes to mind :)
> #ifndef VM_GROWSUP
> # define VM_GROWSUP VM_NONE
> #endif
> @@ -646,6 +648,11 @@ static inline bool vma_is_accessible(struct vm_area_struct *vma)
> return vma->vm_flags & VM_ACCESS_FLAGS;
> }
>
> +static inline bool vma_is_kvm_protected(struct vm_area_struct *vma)
Ditto
> +{
> + return vma->vm_flags & VM_KVM_PROTECTED;
> +}
> +
> #ifdef CONFIG_SHMEM
> /*
> * The vma_is_shmem is not inline because it is used only by slow
> @@ -2773,6 +2780,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
> #define FOLL_LONGTERM 0x10000 /* mapping lifetime is indefinite: see below */
> #define FOLL_SPLIT_PMD 0x20000 /* split huge pmd before returning */
> #define FOLL_PIN 0x40000 /* pages must be released via unpin_user_page */
> +#define FOLL_KVM 0x80000 /* access to VM_KVM_PROTECTED VMAs */
Maybe
FOLL_DM 0x80000 /* access memory dropped from the direct map */
> /*
> * FOLL_PIN and FOLL_LONGTERM may be used in various combinations with each
> diff --git a/mm/gup.c b/mm/gup.c
> index 87a6a59fe667..bd7b9484b35a 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
...
> diff --git a/mm/mmap.c b/mm/mmap.c
> index f609e9ec4a25..d56c3f6efc99 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -112,6 +112,9 @@ pgprot_t vm_get_page_prot(unsigned long vm_flags)
> (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
> pgprot_val(arch_vm_get_page_prot(vm_flags)));
>
> + if (vm_flags & VM_KVM_PROTECTED)
> + ret = PAGE_NONE;
Nit: vma_is_kvm_protected()?
> +
> return arch_filter_pgprot(ret);
> }
> EXPORT_SYMBOL(vm_get_page_prot);
> diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
> index 15e5b037f92d..7663e962510a 100644
> --- a/virt/kvm/async_pf.c
> +++ b/virt/kvm/async_pf.c
> @@ -60,8 +60,8 @@ static void async_pf_execute(struct work_struct *work)
> * access remotely.
> */
> down_read(&mm->mmap_sem);
> - get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
> - &locked);
> + get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE | FOLL_KVM, NULL,
> + NULL, &locked);
> if (locked)
> up_read(&mm->mmap_sem);
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 033471f71dae..530af95efdf3 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1727,7 +1727,7 @@ unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *w
>
> static inline int check_user_page_hwpoison(unsigned long addr)
> {
> - int rc, flags = FOLL_HWPOISON | FOLL_WRITE;
> + int rc, flags = FOLL_HWPOISON | FOLL_WRITE | FOLL_KVM;
>
> rc = get_user_pages(addr, 1, flags, NULL, NULL);
> return rc == -EHWPOISON;
> @@ -1771,7 +1771,7 @@ static bool hva_to_pfn_fast(unsigned long addr, bool write_fault,
> static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
> bool *writable, kvm_pfn_t *pfn)
> {
> - unsigned int flags = FOLL_HWPOISON;
> + unsigned int flags = FOLL_HWPOISON | FOLL_KVM;
> struct page *page;
> int npages = 0;
>
> @@ -2255,7 +2255,7 @@ int copy_from_guest(void *data, unsigned long hva, int len)
> int npages, seg;
>
> while ((seg = next_segment(len, offset)) != 0) {
> - npages = get_user_pages_unlocked(hva, 1, &page, 0);
> + npages = get_user_pages_unlocked(hva, 1, &page, FOLL_KVM);
> if (npages != 1)
> return -EFAULT;
> memcpy(data, page_address(page) + offset, seg);
> @@ -2275,7 +2275,8 @@ int copy_to_guest(unsigned long hva, const void *data, int len)
> int npages, seg;
>
> while ((seg = next_segment(len, offset)) != 0) {
> - npages = get_user_pages_unlocked(hva, 1, &page, FOLL_WRITE);
> + npages = get_user_pages_unlocked(hva, 1, &page,
> + FOLL_WRITE | FOLL_KVM);
> if (npages != 1)
> return -EFAULT;
> memcpy(page_address(page) + offset, data, seg);
> --
> 2.26.2
>
>
--
Sincerely yours,
Mike.
next prev parent reply other threads:[~2020-05-26 6:16 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
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 [this message]
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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