diff mbox series

[25/34] KVM: selftests: Add helpers to convert guest memory b/w private and shared

Message ID 20231105163040.14904-26-pbonzini@redhat.com (mailing list archive)
State New, archived
Headers show
Series KVM: guest_memfd() and per-page attributes | expand

Commit Message

Paolo Bonzini Nov. 5, 2023, 4:30 p.m. UTC
From: Vishal Annapurve <vannapurve@google.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.
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@google.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20231027182217.3615211-28-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 .../selftests/kvm/include/kvm_util_base.h     | 48 +++++++++++++++++++
 tools/testing/selftests/kvm/lib/kvm_util.c    | 28 +++++++++++
 2 files changed, 76 insertions(+)

Comments

Fuad Tabba Nov. 6, 2023, 11:24 a.m. UTC | #1
On Sun, Nov 5, 2023 at 4:34 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> From: Vishal Annapurve <vannapurve@google.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@google.com>
> Co-developed-by: Sean Christopherson <seanjc@google.com>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> Message-Id: <20231027182217.3615211-28-seanjc@google.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.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@google.com>
Tested-by: Fuad Tabba <tabba@google.com>

Cheers,
/fuad

> --
> 2.39.1
>
>
Sean Christopherson Nov. 6, 2023, 4:13 p.m. UTC | #2
On Mon, Nov 06, 2023, Fuad Tabba wrote:
> On Sun, Nov 5, 2023 at 4:34 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
> > +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?

I simply forgot to remove them when I changed the function to support spanning
multiple memslots, i.e. when the code went from this

	fd_offset = region->region.gmem_offset +
		    (gpa - region->region.guest_phys_addr);

to what you see above.
Fuad Tabba Nov. 6, 2023, 4:24 p.m. UTC | #3
On Mon, Nov 6, 2023 at 4:13 PM Sean Christopherson <seanjc@google.com> wrote:
>
> On Mon, Nov 06, 2023, Fuad Tabba wrote:
> > On Sun, Nov 5, 2023 at 4:34 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
> > > +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?
>
> I simply forgot to remove them when I changed the function to support spanning
> multiple memslots, i.e. when the code went from this
>
>         fd_offset = region->region.gmem_offset +
>                     (gpa - region->region.guest_phys_addr);
>
> to what you see above.

I wasn't actually expecting an answer, but I literally _did_ ask for it :)

Thanks,
/fuad
diff mbox series

Patch

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);
+		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)
 {