[PATCH 10/16] KVM: riscv: selftests: Add mmio test
Charlie Jenkins via B4 Relay
devnull+thecharlesjenkins.gmail.com at kernel.org
Tue Apr 7 21:45:58 PDT 2026
From: Charlie Jenkins <thecharlesjenkins at gmail.com>
Use the test KVM device to validate that reads and writes to a device
are properly emulated by KVM. This test checks all load and store
instructions that are emulated by KVM.
Signed-off-by: Charlie Jenkins <thecharlesjenkins at gmail.com>
---
tools/testing/selftests/kvm/Makefile.kvm | 1 +
tools/testing/selftests/kvm/riscv/mmio_test.c | 184 ++++++++++++++++++++++++++
2 files changed, 185 insertions(+)
diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
index ba5c2b643efa..d402fb339bc0 100644
--- a/tools/testing/selftests/kvm/Makefile.kvm
+++ b/tools/testing/selftests/kvm/Makefile.kvm
@@ -204,6 +204,7 @@ TEST_GEN_PROGS_s390 += rseq_test
TEST_GEN_PROGS_riscv = $(TEST_GEN_PROGS_COMMON)
TEST_GEN_PROGS_riscv += riscv/sbi_pmu_test
TEST_GEN_PROGS_riscv += riscv/ebreak_test
+TEST_GEN_PROGS_riscv += riscv/mmio_test
TEST_GEN_PROGS_riscv += access_tracking_perf_test
TEST_GEN_PROGS_riscv += arch_timer
TEST_GEN_PROGS_riscv += coalesced_io_test
diff --git a/tools/testing/selftests/kvm/riscv/mmio_test.c b/tools/testing/selftests/kvm/riscv/mmio_test.c
new file mode 100644
index 000000000000..9726860a269a
--- /dev/null
+++ b/tools/testing/selftests/kvm/riscv/mmio_test.c
@@ -0,0 +1,184 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * mmio_test.c - Tests the mmio functionality.
+ */
+#include "kvm_util.h"
+#include "ucall_common.h"
+
+#define MMIO_TEST_REGION 0x20000000
+
+#define test_standard_read(len, instruction, name, options) \
+static void test_##name(void) \
+{ \
+ unsigned long mmio_result, reference_result; \
+ /* Configure the MMIO to return 0xff for each byte to check sign extension */ \
+ unsigned long reference = ((unsigned long)-1 >> ((sizeof(long) - len) * 8)); \
+ *((unsigned long *)MMIO_TEST_REGION) = reference; \
+ /* Check that reads through MMIO are equivalent to standard reads. */ \
+ asm volatile ( \
+ ".option push\n" \
+ options \
+ #instruction " %[mmio_res], 0(%[region])\n" \
+ #instruction " %[ref_res], 0(%[ref])\n" \
+ ".option pop\n" \
+ : [mmio_res] "=&cr" (mmio_result), [ref_res] "=&cr" (reference_result) \
+ : [region] "cr" (MMIO_TEST_REGION), [ref] "cr" (&reference) \
+ ); \
+ GUEST_ASSERT_EQ(mmio_result, reference_result); \
+ GUEST_DONE(); \
+}
+
+#define test_sp_read(len, instruction, name) \
+static void test_##name(void) \
+{ \
+ unsigned long mmio_result, reference_result; \
+ unsigned long tmp; \
+ /* Configure the MMIO to return 0xff for each byte to check sign extension */ \
+ unsigned long reference = ((unsigned long)-1 >> ((sizeof(long) - len) * 8)); \
+ *(((unsigned long *)MMIO_TEST_REGION)) = reference; \
+ /* Check that reads through MMIO are equivalent to standard reads. */ \
+ asm volatile ( \
+ "mv %[tmp], sp\n" \
+ "mv sp, %[region]\n" \
+ ".option push\n" \
+ ".option arch,+c\n" \
+ #instruction " %[mmio_res], 0(sp)\n" \
+ "mv sp, %[ref]\n" \
+ #instruction " %[ref_res], 0(sp)\n" \
+ ".option pop\n" \
+ "mv sp, %[tmp]\n" \
+ : [mmio_res] "=&cr" (mmio_result), [ref_res] "=&cr" (reference_result), \
+ [tmp] "=&r" (tmp) \
+ : [region] "r" (MMIO_TEST_REGION), [ref] "cr" (&reference) \
+ ); \
+ GUEST_ASSERT_EQ(mmio_result, reference_result); \
+ GUEST_DONE(); \
+}
+
+test_standard_read(1, lb, lb, "")
+test_standard_read(1, lbu, lbu, "")
+test_standard_read(4, lw, lw, "")
+test_standard_read(4, c.lw, c_lw, ".option arch,+c\n")
+test_sp_read(4, c.lwsp, c_lwsp)
+
+#if __riscv_xlen == 64
+test_standard_read(2, lh, lh, "")
+test_standard_read(2, lhu, lhu, "")
+test_standard_read(4, lwu, lwu, "")
+test_standard_read(8, ld, ld, "")
+test_standard_read(8, c.ld, c_ld, ".option arch,+c\n")
+test_sp_read(8, c.ldsp, c_ldsp)
+#endif
+
+#define test_standard_write(len, write, read, name, options) \
+static void test_##name(void) \
+{ \
+ unsigned long result; \
+ unsigned long reference = (0x55555555UL >> ((sizeof(long) - len) * 8)); \
+ /* Check that we can write and then read the same value. */ \
+ asm volatile ( \
+ ".option push\n" \
+ options \
+ #write " %[ref], 0(%[region])\n" \
+ #read " %[res], 0(%[region])\n" \
+ ".option pop\n" \
+ : [res] "=&cr" (result) \
+ : [region] "cr" (MMIO_TEST_REGION), [ref] "cr" (reference) \
+ ); \
+ GUEST_ASSERT_EQ(result, reference); \
+ GUEST_DONE(); \
+}
+
+#define test_sp_write(len, write, read, name) \
+static void test_##name(void) \
+{ \
+ unsigned long result; \
+ unsigned long tmp; \
+ unsigned long reference = (0x55555555UL >> ((sizeof(long) - len) * 8)); \
+ /* Check that we can write and then read the same value. */ \
+ asm volatile ( \
+ "mv %[tmp], sp\n" \
+ "mv sp, %[region]\n" \
+ ".option push\n" \
+ ".option arch,+c\n" \
+ #write " %[ref], 0(sp)\n" \
+ #read " %[res], 0(sp)\n" \
+ ".option pop\n" \
+ "mv sp, %[tmp]\n" \
+ : [res] "=&cr" (result), [tmp] "=&r" (tmp) \
+ : [region] "cr" (MMIO_TEST_REGION), [ref] "cr" (reference) \
+ ); \
+ GUEST_ASSERT_EQ(result, reference); \
+ GUEST_DONE(); \
+}
+
+test_standard_write(1, sb, lb, sb, "")
+test_standard_write(2, sh, lh, sh, "")
+test_standard_write(4, sw, lw, sw, "")
+test_standard_write(4, c.sw, c.lw, c_sw, ".option arch,+c\n")
+test_sp_write(4, c.swsp, c.lwsp, c_swsp)
+
+#if __riscv_xlen == 64
+test_standard_write(8, sd, ld, sd, "")
+test_standard_write(8, c.sd, c.ld, c_sd, ".option arch,+c\n")
+#endif
+
+static void run(void *guest_code, char *instruction)
+{
+ struct ucall uc;
+ struct kvm_vm *vm;
+ struct kvm_vcpu *vcpu;
+
+ vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+ kvm_create_device(vm, KVM_DEV_TYPE_TEST);
+
+ virt_map(vm, (unsigned long)MMIO_TEST_REGION, MMIO_TEST_REGION, 1);
+
+ vcpu_run(vcpu);
+
+ TEST_ASSERT(get_ucall(vcpu, &uc) == UCALL_DONE,
+ "MMIO with instruction '%s' failed: '%s'", instruction,
+ uc.buffer);
+
+ kvm_vm_free(vm);
+}
+
+void test_mmio_read_sign_extension(void)
+{
+ run(test_lb, "lb");
+ run(test_lbu, "lbu");
+ run(test_lw, "lw");
+ run(test_c_lw, "c.lw");
+ run(test_c_lwsp, "c.lwsp");
+
+#if __riscv_xlen == 64
+ run(test_lh, "lh");
+ run(test_lhu, "lhu");
+ run(test_lwu, "lwu");
+ run(test_ld, "ld");
+ run(test_c_ld, "c.ld");
+ run(test_c_ldsp, "c.ldsp");
+#endif
+}
+
+void test_mmio_write(void)
+{
+ run(test_sb, "sb");
+ run(test_sh, "sh");
+ run(test_sw, "sw");
+ run(test_c_sw, "c.sw");
+ run(test_c_swsp, "c.swsp");
+
+#if __riscv_xlen == 64
+ run(test_sd, "sd");
+ run(test_c_sd, "c.sd");
+#endif
+}
+
+int main(void)
+{
+ test_mmio_read_sign_extension();
+ test_mmio_write();
+
+ return 0;
+}
--
2.52.0
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