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Message-ID: <CA+EHjTyjeKymYaJ3kTpVzRFPLKxeDEf9B-DGo7xif_FPN1dFBQ@mail.gmail.com>
Date: Mon, 6 Nov 2023 11:26:13 +0000
From: Fuad Tabba <tabba@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, 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>,
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 v13 27/35] KVM: selftests: Add helpers to convert guest
memory b/w private and shared
On Fri, Oct 27, 2023 at 7:23 PM Sean Christopherson <seanjc@...gle.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.
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>
> ---
> .../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 45050f54701a..a140aee8d0f5 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -1176,6 +1176,34 @@ 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_PRIVATE,
> + "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);
> + }
> +}
> +
Nits aside:
Reviewed-by: Fuad Tabba <tabba@...gle.com>
Tested-by: Fuad Tabba <tabba@...gle.com>
Cheers,
/fuad
> /* Returns the size of a vCPU's kvm_run structure. */
> static int vcpu_mmap_sz(void)
> {
> --
> 2.42.0.820.g83a721a137-goog
>
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