Re: [PATCH v2 1/3] selftests: kvm: s390: Add uc_map_unmap VM test case

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Mon,  2 Sep 2024 13:50:00 +0200
Christoph Schlameuss <schlameuss@linux.ibm.com> wrote:

> Add a test case verifying basic running and interaction of ucontrol VMs.
> Fill the segment and page tables for allocated memory and map memory on
> first access.
> 
> * uc_map_unmap
>   Store and load data to mapped and unmapped memory and use pic segment
>   translation handling to map memory on access.
> 
> Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> ---
>  .../selftests/kvm/s390x/ucontrol_test.c       | 121 +++++++++++++++++-
>  1 file changed, 120 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/kvm/s390x/ucontrol_test.c b/tools/testing/selftests/kvm/s390x/ucontrol_test.c
> index 030c59010fe1..04a0d55af617 100644
> --- a/tools/testing/selftests/kvm/s390x/ucontrol_test.c
> +++ b/tools/testing/selftests/kvm/s390x/ucontrol_test.c
> @@ -16,7 +16,11 @@
>  #include <linux/capability.h>
>  #include <linux/sizes.h>
>  
> +#define PGM_SEGMENT_TRANSLATION 0x10
> +
>  #define VM_MEM_SIZE (4 * SZ_1M)
> +#define VM_MEM_EXT_SIZE (2 * SZ_1M)
> +#define VM_MEM_MAX_M ((VM_MEM_SIZE + VM_MEM_EXT_SIZE) / SZ_1M)
>  
>  /* so directly declare capget to check caps without libcap */
>  int capget(cap_user_header_t header, cap_user_data_t data);
> @@ -58,6 +62,23 @@ asm("test_gprs_asm:\n"
>  	"	j	0b\n"
>  );
>  
> +/* Test program manipulating memory */
> +extern char test_mem_asm[];
> +asm("test_mem_asm:\n"
> +	"xgr	%r0, %r0\n"
> +
> +	"0:\n"
> +	"	ahi	%r0,1\n"
> +	"	st	%r1,0(%r5,%r6)\n"
> +
> +	"	xgr	%r1,%r1\n"
> +	"	l	%r1,0(%r5,%r6)\n"
> +	"	ahi	%r0,1\n"
> +	"	diag	0,0,0x44\n"
> +
> +	"	j	0b\n"
> +);
> +
>  FIXTURE(uc_kvm)
>  {
>  	struct kvm_s390_sie_block *sie_block;
> @@ -67,6 +88,7 @@ FIXTURE(uc_kvm)
>  	uintptr_t base_hva;
>  	uintptr_t code_hva;
>  	int kvm_run_size;
> +	vm_paddr_t pgd;
>  	void *vm_mem;
>  	int vcpu_fd;
>  	int kvm_fd;
> @@ -116,7 +138,7 @@ FIXTURE_SETUP(uc_kvm)
>  	self->base_gpa = 0;
>  	self->code_gpa = self->base_gpa + (3 * SZ_1M);
>  
> -	self->vm_mem = aligned_alloc(SZ_1M, VM_MEM_SIZE);
> +	self->vm_mem = aligned_alloc(SZ_1M, VM_MEM_MAX_M * SZ_1M);
>  	ASSERT_NE(NULL, self->vm_mem) TH_LOG("malloc failed %u", errno);
>  	self->base_hva = (uintptr_t)self->vm_mem;
>  	self->code_hva = self->base_hva - self->base_gpa + self->code_gpa;
> @@ -222,6 +244,36 @@ TEST(uc_cap_hpage)
>  	close(kvm_fd);
>  }
>  
> +/* calculate host virtual addr from guest physical addr */
> +static void *gpa2hva(FIXTURE_DATA(uc_kvm) * self, u64 gpa)
> +{
> +	return (void *)(self->base_hva - self->base_gpa + gpa);
> +}
> +
> +static void uc_handle_exit_ucontrol(FIXTURE_DATA(uc_kvm) * self)
> +{
> +	struct kvm_run *run = self->run;
> +
> +	TEST_ASSERT_EQ(KVM_EXIT_S390_UCONTROL, run->exit_reason);
> +	switch (run->s390_ucontrol.pgm_code) {
> +	case PGM_SEGMENT_TRANSLATION:
> +		pr_info("ucontrol pic segment translation 0x%llx\n",
> +			run->s390_ucontrol.trans_exc_code);
> +		/* map / make additional memory available */
> +		struct kvm_s390_ucas_mapping map2 = {
> +			.user_addr = (u64)gpa2hva(self, run->s390_ucontrol.trans_exc_code),
> +			.vcpu_addr = run->s390_ucontrol.trans_exc_code,
> +			.length = VM_MEM_EXT_SIZE,
> +		};

you could use the wrapper here too (see below)

> +		pr_info("ucas map %p %p 0x%llx\n",
> +			(void *)map2.user_addr, (void *)map2.vcpu_addr, map2.length);
> +		TEST_ASSERT_EQ(0, ioctl(self->vcpu_fd, KVM_S390_UCAS_MAP, &map2));
> +		break;

so this will always return true

> +	default:
> +		TEST_FAIL("UNEXPECTED PGM CODE %d", run->s390_ucontrol.pgm_code);
> +	}
> +}
> +
>  /* verify SIEIC exit
>   * * reset stop requests
>   * * fail on codes not expected in the test cases
> @@ -256,6 +308,12 @@ static bool uc_handle_exit(FIXTURE_DATA(uc_kvm) * self)
>  	struct kvm_run *run = self->run;
>  
>  	switch (run->exit_reason) {
> +	case KVM_EXIT_S390_UCONTROL:
> +		/** check program interruption code
> +		 * handle page fault --> ucas map
> +		 */
> +		uc_handle_exit_ucontrol(self);
> +		break;
>  	case KVM_EXIT_S390_SIEIC:
>  		return uc_handle_sieic(self);
>  	default:
> @@ -287,6 +345,67 @@ static void uc_assert_diag44(FIXTURE_DATA(uc_kvm) * self)
>  	TEST_ASSERT_EQ(0x440000, sie_block->ipb);
>  }
>  
> +TEST_F(uc_kvm, uc_map_unmap)
> +{
> +	struct kvm_sync_regs *sync_regs = &self->run->s.regs;
> +	struct kvm_run *run = self->run;
> +	int rc;
> +
> +	/* copy test_mem_asm to code_hva / code_gpa */
> +	TH_LOG("copy code %p to vm mapped memory %p / %p",
> +	       &test_mem_asm, (void *)self->code_hva, (void *)self->code_gpa);
> +	memcpy((void *)self->code_hva, &test_mem_asm, PAGE_SIZE);
> +
> +	/* DAT disabled + 64 bit mode */
> +	run->psw_mask = 0x0000000180000000ULL;
> +	run->psw_addr = self->code_gpa;
> +
> +	/* set register content for test_mem_asm to access not mapped memory*/
> +	sync_regs->gprs[1] = 0x55;
> +	sync_regs->gprs[5] = self->base_gpa;
> +	sync_regs->gprs[6] = VM_MEM_SIZE;
> +	run->kvm_dirty_regs |= KVM_SYNC_GPRS;
> +
> +	/* run and expect to fail with ucontrol pic segment translation */
> +	ASSERT_EQ(0, uc_run_once(self));
> +	ASSERT_EQ(1, sync_regs->gprs[0]);
> +	ASSERT_EQ(KVM_EXIT_S390_UCONTROL, run->exit_reason);
> +
> +	ASSERT_EQ(PGM_SEGMENT_TRANSLATION, run->s390_ucontrol.pgm_code);
> +	ASSERT_EQ(self->base_gpa + VM_MEM_SIZE, run->s390_ucontrol.trans_exc_code);
> +	/* map / make additional memory available */
> +	struct kvm_s390_ucas_mapping map2 = {
> +		.user_addr = (u64)gpa2hva(self, self->base_gpa + VM_MEM_SIZE),
> +		.vcpu_addr = self->base_gpa + VM_MEM_SIZE,
> +		.length = VM_MEM_EXT_SIZE,
> +	};
> +	TH_LOG("ucas map %p %p 0x%llx",
> +	       (void *)map2.user_addr, (void *)map2.vcpu_addr,
> map2.length);
> +	rc = ioctl(self->vcpu_fd, KVM_S390_UCAS_MAP, &map2);

maybe you can put the map/unmap IOCTLs in a wrapper, so that this
becomes more readable? 

rc = uc_map_ext(self->base_gpa + VM_MEM_SIZE, self->base_gpa +VM_MEM_SIZE);

> +	ASSERT_EQ(0, rc)
> +		TH_LOG("ucas map result %d not expected, %s", rc, strerror(errno));
> +	ASSERT_EQ(0, uc_run_once(self));
> +	ASSERT_EQ(false, uc_handle_exit(self));
> +	uc_assert_diag44(self);
> +
> +	/* assert registers and memory are in expected state */
> +	ASSERT_EQ(2, sync_regs->gprs[0]);
> +	ASSERT_EQ(0x55, sync_regs->gprs[1]);
> +	ASSERT_EQ(0x55, *(u32 *)gpa2hva(self, self->base_gpa + VM_MEM_SIZE));
> +
> +	/* unmap and run loop again */
> +	TH_LOG("ucas unmap %p %p 0x%llx",
> +	       (void *)map2.user_addr, (void *)map2.vcpu_addr, map2.length);
> +	rc = ioctl(self->vcpu_fd, KVM_S390_UCAS_UNMAP, &map2);
> +	ASSERT_EQ(0, rc)
> +		TH_LOG("ucas unmap result %d not expected, %s", rc, strerror(errno));
> +	ASSERT_EQ(0, uc_run_once(self));
> +	ASSERT_EQ(3, sync_regs->gprs[0]);
> +	ASSERT_EQ(KVM_EXIT_S390_UCONTROL, run->exit_reason);
> +	ASSERT_EQ(PGM_SEGMENT_TRANSLATION, run->s390_ucontrol.pgm_code);
> +	ASSERT_EQ(true, uc_handle_exit(self));
> +}
> +
>  TEST_F(uc_kvm, uc_gprs)
>  {
>  	struct kvm_sync_regs *sync_regs = &self->run->s.regs;