KVM: s390: selftests: Add uc_map_unmap VM test case

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>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Link:
https://lore.kernel.org/r/20241107141024.238916-2-schlameuss@linux.ibm.com
[frankja@linux.ibm.com: Fixed patch prefix]
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-ID: <20241107141024.238916-2-schlameuss@linux.ibm.com>

Author: schlac

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 +244,60 @@ 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);
+}
+
+/* map / make additional memory available */
+static int uc_map_ext(FIXTURE_DATA(uc_kvm) *self, u64 vcpu_addr, u64 length)
+{
+	struct kvm_s390_ucas_mapping map = {
+		.user_addr = (u64)gpa2hva(self, vcpu_addr),
+		.vcpu_addr = vcpu_addr,
+		.length = length,
+	};
+	pr_info("ucas map %p %p 0x%llx",
+		(void *)map.user_addr, (void *)map.vcpu_addr, map.length);
+	return ioctl(self->vcpu_fd, KVM_S390_UCAS_MAP, &map);
+}
+
+/* unmap previously mapped memory */
+static int uc_unmap_ext(FIXTURE_DATA(uc_kvm) *self, u64 vcpu_addr, u64 length)
+{
+	struct kvm_s390_ucas_mapping map = {
+		.user_addr = (u64)gpa2hva(self, vcpu_addr),
+		.vcpu_addr = vcpu_addr,
+		.length = length,
+	};
+	pr_info("ucas unmap %p %p 0x%llx",
+		(void *)map.user_addr, (void *)map.vcpu_addr, map.length);
+	return ioctl(self->vcpu_fd, KVM_S390_UCAS_UNMAP, &map);
+}
+
+/* handle ucontrol exit by mapping the accessed segment */
+static void uc_handle_exit_ucontrol(FIXTURE_DATA(uc_kvm) *self)
+{
+	struct kvm_run *run = self->run;
+	u64 seg_addr;
+	int rc;
+
+	TEST_ASSERT_EQ(KVM_EXIT_S390_UCONTROL, run->exit_reason);
+	switch (run->s390_ucontrol.pgm_code) {
+	case PGM_SEGMENT_TRANSLATION:
+		seg_addr = run->s390_ucontrol.trans_exc_code & ~(SZ_1M - 1);
+		pr_info("ucontrol pic segment translation 0x%llx, mapping segment 0x%lx\n",
+			run->s390_ucontrol.trans_exc_code, seg_addr);
+		/* map / make additional memory available */
+		rc = uc_map_ext(self, seg_addr, SZ_1M);
+		TEST_ASSERT_EQ(0, rc);
+		break;
+	default:
+		TEST_FAIL("UNEXPECTED PGM CODE %d", run->s390_ucontrol.pgm_code);
+	}
+}
+
 /* verify SIEIC exit
  * * fail on codes not expected in the test cases
  */
@@ -255,6 +331,12 @@ 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:
@@ -286,6 +368,67 @@ 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;
+	const u64 disp = 1;
+	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 + disp;
+	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);
+
+	/* fail to map memory with not segment aligned address */
+	rc = uc_map_ext(self, self->base_gpa + VM_MEM_SIZE + disp, VM_MEM_EXT_SIZE);
+	ASSERT_GT(0, rc)
+		TH_LOG("ucas map for non segment address should fail but didn't; "
+		       "result %d not expected, %s", rc, strerror(errno));
+
+	/* map / make additional memory available */
+	rc = uc_map_ext(self, self->base_gpa + VM_MEM_SIZE, VM_MEM_EXT_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 + disp));
+
+	/* unmap and run loop again */
+	rc = uc_unmap_ext(self, self->base_gpa + VM_MEM_SIZE, VM_MEM_EXT_SIZE);
+	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);
+	/* handle ucontrol exit and remap memory after previous map and unmap */
+	ASSERT_EQ(true, uc_handle_exit(self));
+}
+
 TEST_F(uc_kvm, uc_gprs)
 {
 	struct kvm_sync_regs *sync_regs = &self->run->s.regs;