Re: [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION

[Christian Borntraeger <borntraeger@de.ibm.com>]

On 17.12.19 21:40, Sean Christopherson wrote:
> Add a KVM selftest to test moving the base gfn of a userspace memory
> region.  The test is primarily targeted at x86 to verify its memslot
> metadata is correctly updated, but also provides basic functionality
> coverage on other architectures.

This fails to build on s390 (and probably others)

set_memory_region_test.c: In function ‘test_move_memory_region’:
set_memory_region_test.c:78:2: warning: implicit declaration of function ‘vcpu_set_cpuid’ [-Wimplicit-function-declaration]
   78 |  vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
      |  ^~~~~~~~~~~~~~
set_memory_region_test.c:78:30: warning: implicit declaration of function ‘kvm_get_supported_cpuid’ [-Wimplicit-function-declaration]
   78 |  vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
      |                              ^~~~~~~~~~~~~~~~~~~~~~~


> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
>  tools/testing/selftests/kvm/.gitignore        |   1 +
>  tools/testing/selftests/kvm/Makefile          |   3 +
>  .../testing/selftests/kvm/include/kvm_util.h  |   1 +
>  tools/testing/selftests/kvm/lib/kvm_util.c    |  30 ++++
>  .../selftests/kvm/set_memory_region_test.c    | 142 ++++++++++++++++++
>  5 files changed, 177 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/set_memory_region_test.c
> 
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index 30072c3f52fb..6f60ceb81440 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -17,3 +17,4 @@
>  /clear_dirty_log_test
>  /dirty_log_test
>  /kvm_create_max_vcpus
> +/set_memory_region_test
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 3138a916574a..01c79e02c5b7 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -29,15 +29,18 @@ TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
>  TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
>  TEST_GEN_PROGS_x86_64 += dirty_log_test
>  TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
> +TEST_GEN_PROGS_x86_64 += set_memory_region_test
>  
>  TEST_GEN_PROGS_aarch64 += clear_dirty_log_test
>  TEST_GEN_PROGS_aarch64 += dirty_log_test
>  TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
> +TEST_GEN_PROGS_aarch64 += set_memory_region_test
>  
>  TEST_GEN_PROGS_s390x = s390x/memop
>  TEST_GEN_PROGS_s390x += s390x/sync_regs_test
>  TEST_GEN_PROGS_s390x += dirty_log_test
>  TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
> +TEST_GEN_PROGS_s390x += set_memory_region_test
>  
>  TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
>  LIBKVM += $(LIBKVM_$(UNAME_M))
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 29cccaf96baf..15d3b8690ffb 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -100,6 +100,7 @@ int _vcpu_ioctl(struct kvm_vm *vm, uint32_t vcpuid, unsigned long ioctl,
>  		void *arg);
>  void vm_ioctl(struct kvm_vm *vm, unsigned long ioctl, void *arg);
>  void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags);
> +void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa);
>  void vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpuid);
>  vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min,
>  			  uint32_t data_memslot, uint32_t pgd_memslot);
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 41cf45416060..464a75ce9843 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -756,6 +756,36 @@ void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags)
>  		ret, errno, slot, flags);
>  }
>  
> +/*
> + * VM Memory Region Move
> + *
> + * Input Args:
> + *   vm - Virtual Machine
> + *   slot - Slot of the memory region to move
> + *   flags - Starting guest physical address
> + *
> + * Output Args: None
> + *
> + * Return: None
> + *
> + * Change the gpa of a memory region.
> + */
> +void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa)
> +{
> +	struct userspace_mem_region *region;
> +	int ret;
> +
> +	region = memslot2region(vm, slot);
> +
> +	region->region.guest_phys_addr = new_gpa;
> +
> +	ret = ioctl(vm->fd, KVM_SET_USER_MEMORY_REGION, &region->region);
> +
> +	TEST_ASSERT(!ret, "KVM_SET_USER_MEMORY_REGION failed\n"
> +		    "ret: %i errno: %i slot: %u flags: 0x%x",
> +		    ret, errno, slot, new_gpa);
> +}
> +
>  /*
>   * VCPU mmap Size
>   *
> diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
> new file mode 100644
> index 000000000000..c9603b95ccf7
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/set_memory_region_test.c
> @@ -0,0 +1,142 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#define _GNU_SOURCE /* for program_invocation_short_name */
> +#include <fcntl.h>
> +#include <pthread.h>
> +#include <sched.h>
> +#include <signal.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/ioctl.h>
> +
> +#include <linux/compiler.h>
> +
> +#include <test_util.h>
> +#include <kvm_util.h>
> +#include <processor.h>
> +
> +#define VCPU_ID 0
> +
> +/*
> + * 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 (on x86 and arm64).
> + */
> +#define MEM_REGION_GPA		0xc0000000
> +#define MEM_REGION_SIZE		0x200000
> +#define MEM_REGION_SLOT		10
> +
> +static void guest_code(void)
> +{
> +	uint64_t val;
> +
> +	do {
> +		val = READ_ONCE(*((uint64_t *)MEM_REGION_GPA));
> +	} while (!val);
> +
> +	if (val != 1)
> +		ucall(UCALL_ABORT, 1, val);
> +
> +	GUEST_DONE();
> +}
> +
> +static void *vcpu_worker(void *data)
> +{
> +	struct kvm_vm *vm = data;
> +	struct kvm_run *run;
> +	struct ucall uc;
> +	uint64_t cmd;
> +
> +	/*
> +	 * Loop until the guest is done.  Re-enter the guest on all MMIO exits,
> +	 * which will occur if the guest attempts to access a memslot while it
> +	 * is being moved.
> +	 */
> +	run = vcpu_state(vm, VCPU_ID);
> +	do {
> +		vcpu_run(vm, VCPU_ID);
> +	} while (run->exit_reason == KVM_EXIT_MMIO);
> +
> +	TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
> +		    "Unexpected exit reason = %d", run->exit_reason);
> +
> +	cmd = get_ucall(vm, VCPU_ID, &uc);
> +	TEST_ASSERT(cmd == UCALL_DONE, "Unexpected val in guest = %llu",
> +		    uc.args[0]);
> +	return NULL;
> +}
> +
> +static void test_move_memory_region(void)
> +{
> +	pthread_t vcpu_thread;
> +	struct kvm_vm *vm;
> +	uint64_t *hva;
> +	uint64_t gpa;
> +
> +	vm = vm_create_default(VCPU_ID, 0, guest_code);
> +
> +	vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
> +
> +	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS_THP,
> +				    MEM_REGION_GPA, MEM_REGION_SLOT,
> +				    MEM_REGION_SIZE / getpagesize(), 0);
> +
> +	/*
> +	 * Allocate and map two pages so that the GPA accessed by guest_code()
> +	 * stays valid across the memslot move.
> +	 */
> +	gpa = vm_phy_pages_alloc(vm, 2, MEM_REGION_GPA, MEM_REGION_SLOT);
> +	TEST_ASSERT(gpa == MEM_REGION_GPA, "Failed vm_phy_pages_alloc\n");
> +
> +	virt_map(vm, MEM_REGION_GPA, MEM_REGION_GPA, 2 * 4096, 0);
> +
> +	/* Ditto for the host mapping so that both pages can be zeroed. */
> +	hva = addr_gpa2hva(vm, MEM_REGION_GPA);
> +	memset(hva, 0, 2 * 4096);
> +
> +	pthread_create(&vcpu_thread, NULL, vcpu_worker, vm);
> +
> +	/* Ensure the guest thread is spun up. */
> +	usleep(100000);
> +
> +	/*
> +	 * Shift the region's base GPA.  The guest should not see "2" as the
> +	 * hva->gpa translation is misaligned, i.e. the guest is accessing a
> +	 * different host pfn.
> +	 */
> +	vm_mem_region_move(vm, MEM_REGION_SLOT, MEM_REGION_GPA - 4096);
> +	WRITE_ONCE(*hva, 2);
> +
> +	usleep(100000);
> +
> +	/*
> +	 * Note, value in memory needs to be changed *before* restoring the
> +	 * memslot, else the guest could race the update and see "2".
> +	 */
> +	WRITE_ONCE(*hva, 1);
> +
> +	/* Restore the original base, the guest should see "1". */
> +	vm_mem_region_move(vm, MEM_REGION_SLOT, MEM_REGION_GPA);
> +
> +	pthread_join(vcpu_thread, NULL);
> +
> +	kvm_vm_free(vm);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	int i, loops;
> +
> +	/* Tell stdout not to buffer its content */
> +	setbuf(stdout, NULL);
> +
> +	if (argc > 1)
> +		loops = atoi(argv[1]);
> +	else
> +		loops = 10;
> +
> +	for (i = 0; i < loops; i++)
> +		test_move_memory_region();
> +
> +	return 0;
> +}
>