Commit 32ffa4f7 authored by Axel Rasmussen's avatar Axel Rasmussen Committed by Paolo Bonzini
Browse files

KVM: selftests: compute correct demand paging size 



This is a preparatory commit needed before we can use different kinds of
backing pages for guest memory.

Previously, we used perf_test_args.host_page_size, which is the host's
native page size (commonly 4K). For VM_MEM_SRC_ANONYMOUS this turns out
to be okay, but in a follow-up commit we want to allow using different
kinds of backing memory.

Take VM_MEM_SRC_ANONYMOUS_HUGETLB for example. Without this change, if
we used that backing page type, when we issued a UFFDIO_COPY ioctl we'd
only do so with 4K, rather than the full 2M of a backing hugepage. In
this case, UFFDIO_COPY returns -EINVAL (__mcopy_atomic_hugetlb checks
the size).

Signed-off-by: default avatarAxel Rasmussen <axelrasmussen@google.com>
Message-Id: <20210519200339.829146-5-axelrasmussen@google.com>
Reviewed-by: default avatarBen Gardon <bgardon@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 25408e5a

tools/testing/selftests/kvm/demand_paging_test.c

+7 −4
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ 


static int nr_vcpus = 1;

static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;

static size_t demand_paging_size;

static char *guest_data_prototype;



static void *vcpu_worker(void *data)
@@ -84,7 +85,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr) 


	copy.src = (uint64_t)guest_data_prototype;

	copy.dst = addr;

	copy.len = perf_test_args.host_page_size;

	copy.len = demand_paging_size;

	copy.mode = 0;



	clock_gettime(CLOCK_MONOTONIC, &start);
@@ -101,7 +102,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr) 
	PER_PAGE_DEBUG("UFFDIO_COPY %d \t%ld ns\n", tid,

		       timespec_to_ns(ts_diff));

	PER_PAGE_DEBUG("Paged in %ld bytes at 0x%lx from thread %d\n",

		       perf_test_args.host_page_size, addr, tid);

		       demand_paging_size, addr, tid);



	return 0;

}
@@ -260,10 +261,12 @@ static void run_test(enum vm_guest_mode mode, void *arg) 


	perf_test_args.wr_fract = 1;



	guest_data_prototype = malloc(perf_test_args.host_page_size);

	demand_paging_size = get_backing_src_pagesz(VM_MEM_SRC_ANONYMOUS);



	guest_data_prototype = malloc(demand_paging_size);

	TEST_ASSERT(guest_data_prototype,

		    "Failed to allocate buffer for guest data pattern");

	memset(guest_data_prototype, 0xAB, perf_test_args.host_page_size);

	memset(guest_data_prototype, 0xAB, demand_paging_size);



	vcpu_threads = malloc(nr_vcpus * sizeof(*vcpu_threads));

	TEST_ASSERT(vcpu_threads, "Memory allocation failed");