Re: [PATCH 10/10] selftests: kvm: Add testcase for creating max number of memslots

[Wainer dos Santos Moschetta]

On 4/10/20 8:17 PM, Sean Christopherson wrote:
> From: Wainer dos Santos Moschetta <wainersm@xxxxxxxxxx>
>
> This patch introduces test_add_max_memory_regions(), which checks
> that a VM can have added memory slots up to the limit defined in
> KVM_CAP_NR_MEMSLOTS. Then attempt to add one more slot to
> verify it fails as expected.
>
> Signed-off-by: Wainer dos Santos Moschetta <wainersm@xxxxxxxxxx>
> Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
>   .../selftests/kvm/set_memory_region_test.c    | 65 +++++++++++++++++--
>   1 file changed, 60 insertions(+), 5 deletions(-)

Putting the memory region related tests together into a single test file 
makes sense to me.

Acked-by: Wainer dos Santos Moschetta <wainersm@xxxxxxxxxx>

> diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
> index 0f36941ebb96..cdf5024b2452 100644
> --- a/tools/testing/selftests/kvm/set_memory_region_test.c
> +++ b/tools/testing/selftests/kvm/set_memory_region_test.c
> @@ -9,6 +9,7 @@
>   #include <stdlib.h>
>   #include <string.h>
>   #include <sys/ioctl.h>
> +#include <sys/mman.h>
>   
>   #include <linux/compiler.h>
>   
> @@ -18,14 +19,18 @@
>   
>   #define VCPU_ID 0
>   
> -#ifdef __x86_64__
>   /*
> - * Somewhat arbitrary location and slot, intended to not overlap anything.  The
> - * location and size are specifically 2mb sized/aligned so that the initial
> - * region corresponds to exactly one large page.
> + * s390x needs at least 1MB alignment, and the x86_64 MOVE/DELETE tests need a
> + * 2MB sized and aligned region so that the initial region corresponds to
> + * exactly one large page.
>    */
> -#define MEM_REGION_GPA		0xc0000000
>   #define MEM_REGION_SIZE		0x200000
> +
> +#ifdef __x86_64__
> +/*
> + * Somewhat arbitrary location and slot, intended to not overlap anything.
> + */
> +#define MEM_REGION_GPA		0xc0000000
>   #define MEM_REGION_SLOT		10
>   
>   static const uint64_t MMIO_VAL = 0xbeefull;
> @@ -318,6 +323,54 @@ static void test_zero_memory_regions(void)
>   	kvm_vm_free(vm);
>   }
>   
> +/*
> + * Test it can be added memory slots up to KVM_CAP_NR_MEMSLOTS, then any
> + * tentative to add further slots should fail.
> + */
> +static void test_add_max_memory_regions(void)
> +{
> +	int ret;
> +	struct kvm_vm *vm;
> +	uint32_t max_mem_slots;
> +	uint32_t slot;
> +	uint64_t guest_addr = 0x0;
> +	uint64_t mem_reg_npages;
> +	void *mem;
> +
> +	max_mem_slots = kvm_check_cap(KVM_CAP_NR_MEMSLOTS);
> +	TEST_ASSERT(max_mem_slots > 0,
> +		    "KVM_CAP_NR_MEMSLOTS should be greater than 0");
> +	pr_info("Allowed number of memory slots: %i\n", max_mem_slots);
> +
> +	vm = vm_create(VM_MODE_DEFAULT, 0, O_RDWR);
> +
> +	mem_reg_npages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, MEM_REGION_SIZE);
> +
> +	/* Check it can be added memory slots up to the maximum allowed */
> +	pr_info("Adding slots 0..%i, each memory region with %dK size\n",
> +		(max_mem_slots - 1), MEM_REGION_SIZE >> 10);
> +	for (slot = 0; slot < max_mem_slots; slot++) {
> +		vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
> +					    guest_addr, slot, mem_reg_npages,
> +					    0);
> +		guest_addr += MEM_REGION_SIZE;
> +	}
> +
> +	/* Check it cannot be added memory slots beyond the limit */
> +	mem = mmap(NULL, MEM_REGION_SIZE, PROT_READ | PROT_WRITE,
> +		   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> +	TEST_ASSERT(mem != MAP_FAILED, "Failed to mmap() host");
> +
> +	ret = ioctl(vm_get_fd(vm), KVM_SET_USER_MEMORY_REGION,
> +		    &(struct kvm_userspace_memory_region) {slot, 0, guest_addr,
> +		    MEM_REGION_SIZE, (uint64_t) mem});
> +	TEST_ASSERT(ret == -1 && errno == EINVAL,
> +		    "Adding one more memory slot should fail with EINVAL");
> +
> +	munmap(mem, MEM_REGION_SIZE);
> +	kvm_vm_free(vm);
> +}
> +
>   int main(int argc, char *argv[])
>   {
>   #ifdef __x86_64__
> @@ -329,6 +382,8 @@ int main(int argc, char *argv[])
>   
>   	test_zero_memory_regions();
>   
> +	test_add_max_memory_regions();
> +
>   #ifdef __x86_64__
>   	if (argc > 1)
>   		loops = atoi(argv[1]);