linux-kernel - Re: [PATCH 25/34] KVM: selftests: Add helpers to convert guest memory b/w private and shared

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Mon, 6 Nov 2023 11:24:54 +0000
From:   Fuad Tabba <tabba@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Marc Zyngier <maz@...nel.org>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Huacai Chen <chenhuacai@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Anup Patel <anup@...infault.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Sean Christopherson <seanjc@...gle.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>, kvm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        linux-mips@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Xiaoyao Li <xiaoyao.li@...el.com>,
        Xu Yilun <yilun.xu@...el.com>,
        Chao Peng <chao.p.peng@...ux.intel.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Anish Moorthy <amoorthy@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Yu Zhang <yu.c.zhang@...ux.intel.com>,
        Isaku Yamahata <isaku.yamahata@...el.com>,
        Mickaël Salaün <mic@...ikod.net>,
        Vlastimil Babka <vbabka@...e.cz>,
        Vishal Annapurve <vannapurve@...gle.com>,
        Ackerley Tng <ackerleytng@...gle.com>,
        Maciej Szmigiero <mail@...iej.szmigiero.name>,
        David Hildenbrand <david@...hat.com>,
        Quentin Perret <qperret@...gle.com>,
        Michael Roth <michael.roth@....com>,
        Wang <wei.w.wang@...el.com>,
        Liam Merwick <liam.merwick@...cle.com>,
        Isaku Yamahata <isaku.yamahata@...il.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCH 25/34] KVM: selftests: Add helpers to convert guest memory
 b/w private and shared

On Sun, Nov 5, 2023 at 4:34 PM Paolo Bonzini <pbonzini@...hat.com> wrote:
>
> From: Vishal Annapurve <vannapurve@...gle.com>
>
> Add helpers to convert memory between private and shared via KVM's
> memory attributes, as well as helpers to free/allocate guest_memfd memory
> via fallocate().  Userspace, i.e. tests, is NOT required to do fallocate()
> when converting memory, as the attributes are the single source of true.

nit: true->truth

> Provide allocate() helpers so that tests can mimic a userspace that frees
> private memory on conversion, e.g. to prioritize memory usage over
> performance.
>
> Signed-off-by: Vishal Annapurve <vannapurve@...gle.com>
> Co-developed-by: Sean Christopherson <seanjc@...gle.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> Message-Id: <20231027182217.3615211-28-seanjc@...gle.com>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
>  .../selftests/kvm/include/kvm_util_base.h     | 48 +++++++++++++++++++
>  tools/testing/selftests/kvm/lib/kvm_util.c    | 28 +++++++++++
>  2 files changed, 76 insertions(+)
>
> diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
> index 9f861182c02a..1441fca6c273 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util_base.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
> @@ -333,6 +333,54 @@ static inline void vm_enable_cap(struct kvm_vm *vm, uint32_t cap, uint64_t arg0)
>         vm_ioctl(vm, KVM_ENABLE_CAP, &enable_cap);
>  }
>
> +static inline void vm_set_memory_attributes(struct kvm_vm *vm, uint64_t gpa,
> +                                           uint64_t size, uint64_t attributes)
> +{
> +       struct kvm_memory_attributes attr = {
> +               .attributes = attributes,
> +               .address = gpa,
> +               .size = size,
> +               .flags = 0,
> +       };
> +
> +       /*
> +        * KVM_SET_MEMORY_ATTRIBUTES overwrites _all_ attributes.  These flows
> +        * need significant enhancements to support multiple attributes.
> +        */
> +       TEST_ASSERT(!attributes || attributes == KVM_MEMORY_ATTRIBUTE_PRIVATE,
> +                   "Update me to support multiple attributes!");
> +
> +       vm_ioctl(vm, KVM_SET_MEMORY_ATTRIBUTES, &attr);
> +}
> +
> +
> +static inline void vm_mem_set_private(struct kvm_vm *vm, uint64_t gpa,
> +                                     uint64_t size)
> +{
> +       vm_set_memory_attributes(vm, gpa, size, KVM_MEMORY_ATTRIBUTE_PRIVATE);
> +}
> +
> +static inline void vm_mem_set_shared(struct kvm_vm *vm, uint64_t gpa,
> +                                    uint64_t size)
> +{
> +       vm_set_memory_attributes(vm, gpa, size, 0);
> +}
> +
> +void vm_guest_mem_fallocate(struct kvm_vm *vm, uint64_t gpa, uint64_t size,
> +                           bool punch_hole);
> +
> +static inline void vm_guest_mem_punch_hole(struct kvm_vm *vm, uint64_t gpa,
> +                                          uint64_t size)
> +{
> +       vm_guest_mem_fallocate(vm, gpa, size, true);
> +}
> +
> +static inline void vm_guest_mem_allocate(struct kvm_vm *vm, uint64_t gpa,
> +                                        uint64_t size)
> +{
> +       vm_guest_mem_fallocate(vm, gpa, size, false);
> +}
> +
>  void vm_enable_dirty_ring(struct kvm_vm *vm, uint32_t ring_size);
>  const char *vm_guest_mode_string(uint32_t i);
>
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index b63500fca627..95a553400ea9 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -1167,6 +1167,34 @@ void vm_mem_region_delete(struct kvm_vm *vm, uint32_t slot)
>         __vm_mem_region_delete(vm, memslot2region(vm, slot), true);
>  }
>
> +void vm_guest_mem_fallocate(struct kvm_vm *vm, uint64_t base, uint64_t size,
> +                           bool punch_hole)
> +{
> +       const int mode = FALLOC_FL_KEEP_SIZE | (punch_hole ? FALLOC_FL_PUNCH_HOLE : 0);
> +       struct userspace_mem_region *region;
> +       uint64_t end = base + size;
> +       uint64_t gpa, len;
> +       off_t fd_offset;
> +       int ret;
> +
> +       for (gpa = base; gpa < end; gpa += len) {
> +               uint64_t offset;
> +
> +               region = userspace_mem_region_find(vm, gpa, gpa);
> +               TEST_ASSERT(region && region->region.flags & KVM_MEM_GUEST_MEMFD,
> +                           "Private memory region not found for GPA 0x%lx", gpa);
> +
> +               offset = (gpa - region->region.guest_phys_addr);

nit: why the parentheses?

> +               fd_offset = region->region.guest_memfd_offset + offset;
> +               len = min_t(uint64_t, end - gpa, region->region.memory_size - offset);
> +
> +               ret = fallocate(region->region.guest_memfd, mode, fd_offset, len);
> +               TEST_ASSERT(!ret, "fallocate() failed to %s at %lx (len = %lu), fd = %d, mode = %x, offset = %lx\n",
> +                           punch_hole ? "punch hole" : "allocate", gpa, len,
> +                           region->region.guest_memfd, mode, fd_offset);
> +       }
> +}
> +
>  /* Returns the size of a vCPU's kvm_run structure. */
>  static int vcpu_mmap_sz(void)
>  {

Nits aside:

Reviewed-by: Fuad Tabba <tabba@...gle.com>
Tested-by: Fuad Tabba <tabba@...gle.com>

Cheers,
/fuad

> --
> 2.39.1
>
>