]> Git Repo - linux.git/commitdiff
KVM: selftests: Add exception handling support for aarch64
authorRicardo Koller <[email protected]>
Fri, 11 Jun 2021 01:10:19 +0000 (18:10 -0700)
committerMarc Zyngier <[email protected]>
Mon, 14 Jun 2021 08:06:23 +0000 (09:06 +0100)
Add the infrastructure needed to enable exception handling in aarch64
selftests. The exception handling defaults to an unhandled-exception
handler which aborts the test, just like x86. These handlers can be
overridden by calling vm_install_exception_handler(vector) or
vm_install_sync_handler(vector, ec). The unhandled exception reporting
from the guest is done using the ucall type introduced in a previous
commit, UCALL_UNHANDLED.

The exception handling code is inspired on kvm-unit-tests.

Signed-off-by: Ricardo Koller <[email protected]>
Reviewed-by: Andrew Jones <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
tools/testing/selftests/kvm/Makefile
tools/testing/selftests/kvm/include/aarch64/processor.h
tools/testing/selftests/kvm/lib/aarch64/handlers.S [new file with mode: 0644]
tools/testing/selftests/kvm/lib/aarch64/processor.c

index daaee1888b1288143a308a6b011fb8c627f0174e..a77e6063f7e96a470a7f6c2da3962208a0f9ae35 100644 (file)
@@ -35,7 +35,7 @@ endif
 
 LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/rbtree.c lib/sparsebit.c lib/test_util.c lib/guest_modes.c lib/perf_test_util.c
 LIBKVM_x86_64 = lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/svm.c lib/x86_64/ucall.c lib/x86_64/handlers.S
-LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c
+LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c lib/aarch64/handlers.S
 LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c lib/s390x/diag318_test_handler.c
 
 TEST_GEN_PROGS_x86_64 = x86_64/cr4_cpuid_sync_test
index b7fa0c8551db4b2d84dad3fca42572d299e5cdd6..b2b3e9d626cb5aa5bd8e8dc8e8cbd2fdddbef474 100644 (file)
@@ -8,6 +8,7 @@
 #define SELFTEST_KVM_PROCESSOR_H
 
 #include "kvm_util.h"
+#include <linux/stringify.h>
 
 
 #define ARM64_CORE_REG(x) (KVM_REG_ARM64 | KVM_REG_SIZE_U64 | \
@@ -18,6 +19,7 @@
 #define MAIR_EL1       3, 0, 10, 2, 0
 #define TTBR0_EL1      3, 0,  2, 0, 0
 #define SCTLR_EL1      3, 0,  1, 0, 0
+#define VBAR_EL1       3, 0, 12, 0, 0
 
 /*
  * Default MAIR
@@ -56,4 +58,65 @@ void aarch64_vcpu_setup(struct kvm_vm *vm, int vcpuid, struct kvm_vcpu_init *ini
 void aarch64_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid,
                              struct kvm_vcpu_init *init, void *guest_code);
 
+struct ex_regs {
+       u64 regs[31];
+       u64 sp;
+       u64 pc;
+       u64 pstate;
+};
+
+#define VECTOR_NUM     16
+
+enum {
+       VECTOR_SYNC_CURRENT_SP0,
+       VECTOR_IRQ_CURRENT_SP0,
+       VECTOR_FIQ_CURRENT_SP0,
+       VECTOR_ERROR_CURRENT_SP0,
+
+       VECTOR_SYNC_CURRENT,
+       VECTOR_IRQ_CURRENT,
+       VECTOR_FIQ_CURRENT,
+       VECTOR_ERROR_CURRENT,
+
+       VECTOR_SYNC_LOWER_64,
+       VECTOR_IRQ_LOWER_64,
+       VECTOR_FIQ_LOWER_64,
+       VECTOR_ERROR_LOWER_64,
+
+       VECTOR_SYNC_LOWER_32,
+       VECTOR_IRQ_LOWER_32,
+       VECTOR_FIQ_LOWER_32,
+       VECTOR_ERROR_LOWER_32,
+};
+
+#define VECTOR_IS_SYNC(v) ((v) == VECTOR_SYNC_CURRENT_SP0 || \
+                          (v) == VECTOR_SYNC_CURRENT     || \
+                          (v) == VECTOR_SYNC_LOWER_64    || \
+                          (v) == VECTOR_SYNC_LOWER_32)
+
+#define ESR_EC_NUM             64
+#define ESR_EC_SHIFT           26
+#define ESR_EC_MASK            (ESR_EC_NUM - 1)
+
+void vm_init_descriptor_tables(struct kvm_vm *vm);
+void vcpu_init_descriptor_tables(struct kvm_vm *vm, uint32_t vcpuid);
+
+typedef void(*handler_fn)(struct ex_regs *);
+void vm_install_exception_handler(struct kvm_vm *vm,
+               int vector, handler_fn handler);
+void vm_install_sync_handler(struct kvm_vm *vm,
+               int vector, int ec, handler_fn handler);
+
+#define write_sysreg(reg, val)                                           \
+({                                                                       \
+       u64 __val = (u64)(val);                                           \
+       asm volatile("msr " __stringify(reg) ", %x0" : : "rZ" (__val));   \
+})
+
+#define read_sysreg(reg)                                                 \
+({     u64 val;                                                          \
+       asm volatile("mrs %0, "__stringify(reg) : "=r"(val) : : "memory");\
+       val;                                                              \
+})
+
 #endif /* SELFTEST_KVM_PROCESSOR_H */
diff --git a/tools/testing/selftests/kvm/lib/aarch64/handlers.S b/tools/testing/selftests/kvm/lib/aarch64/handlers.S
new file mode 100644 (file)
index 0000000..0e443ea
--- /dev/null
@@ -0,0 +1,126 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+.macro save_registers
+       add     sp, sp, #-16 * 17
+
+       stp     x0, x1, [sp, #16 * 0]
+       stp     x2, x3, [sp, #16 * 1]
+       stp     x4, x5, [sp, #16 * 2]
+       stp     x6, x7, [sp, #16 * 3]
+       stp     x8, x9, [sp, #16 * 4]
+       stp     x10, x11, [sp, #16 * 5]
+       stp     x12, x13, [sp, #16 * 6]
+       stp     x14, x15, [sp, #16 * 7]
+       stp     x16, x17, [sp, #16 * 8]
+       stp     x18, x19, [sp, #16 * 9]
+       stp     x20, x21, [sp, #16 * 10]
+       stp     x22, x23, [sp, #16 * 11]
+       stp     x24, x25, [sp, #16 * 12]
+       stp     x26, x27, [sp, #16 * 13]
+       stp     x28, x29, [sp, #16 * 14]
+
+       /*
+        * This stores sp_el1 into ex_regs.sp so exception handlers can "look"
+        * at it. It will _not_ be used to restore the sp on return from the
+        * exception so handlers can not update it.
+        */
+       add     x1, sp, #16 * 17
+       stp     x30, x1, [sp, #16 * 15] /* x30, SP */
+
+       mrs     x1, elr_el1
+       mrs     x2, spsr_el1
+       stp     x1, x2, [sp, #16 * 16] /* PC, PSTATE */
+.endm
+
+.macro restore_registers
+       ldp     x1, x2, [sp, #16 * 16] /* PC, PSTATE */
+       msr     elr_el1, x1
+       msr     spsr_el1, x2
+
+       /* sp is not restored */
+       ldp     x30, xzr, [sp, #16 * 15] /* x30, SP */
+
+       ldp     x28, x29, [sp, #16 * 14]
+       ldp     x26, x27, [sp, #16 * 13]
+       ldp     x24, x25, [sp, #16 * 12]
+       ldp     x22, x23, [sp, #16 * 11]
+       ldp     x20, x21, [sp, #16 * 10]
+       ldp     x18, x19, [sp, #16 * 9]
+       ldp     x16, x17, [sp, #16 * 8]
+       ldp     x14, x15, [sp, #16 * 7]
+       ldp     x12, x13, [sp, #16 * 6]
+       ldp     x10, x11, [sp, #16 * 5]
+       ldp     x8, x9, [sp, #16 * 4]
+       ldp     x6, x7, [sp, #16 * 3]
+       ldp     x4, x5, [sp, #16 * 2]
+       ldp     x2, x3, [sp, #16 * 1]
+       ldp     x0, x1, [sp, #16 * 0]
+
+       add     sp, sp, #16 * 17
+
+       eret
+.endm
+
+.pushsection ".entry.text", "ax"
+.balign 0x800
+.global vectors
+vectors:
+.popsection
+
+.set   vector, 0
+
+/*
+ * Build an exception handler for vector and append a jump to it into
+ * vectors (while making sure that it's 0x80 aligned).
+ */
+.macro HANDLER, label
+handler_\label:
+       save_registers
+       mov     x0, sp
+       mov     x1, #vector
+       bl      route_exception
+       restore_registers
+
+.pushsection ".entry.text", "ax"
+.balign 0x80
+       b       handler_\label
+.popsection
+
+.set   vector, vector + 1
+.endm
+
+.macro HANDLER_INVALID
+.pushsection ".entry.text", "ax"
+.balign 0x80
+/* This will abort so no need to save and restore registers. */
+       mov     x0, #vector
+       mov     x1, #0 /* ec */
+       mov     x2, #0 /* valid_ec */
+       b       kvm_exit_unexpected_exception
+.popsection
+
+.set   vector, vector + 1
+.endm
+
+/*
+ * Caution: be sure to not add anything between the declaration of vectors
+ * above and these macro calls that will build the vectors table below it.
+ */
+       HANDLER_INVALID                         // Synchronous EL1t
+       HANDLER_INVALID                         // IRQ EL1t
+       HANDLER_INVALID                         // FIQ EL1t
+       HANDLER_INVALID                         // Error EL1t
+
+       HANDLER el1h_sync                       // Synchronous EL1h
+       HANDLER el1h_irq                        // IRQ EL1h
+       HANDLER el1h_fiq                        // FIQ EL1h
+       HANDLER el1h_error                      // Error EL1h
+
+       HANDLER el0_sync_64                     // Synchronous 64-bit EL0
+       HANDLER el0_irq_64                      // IRQ 64-bit EL0
+       HANDLER el0_fiq_64                      // FIQ 64-bit EL0
+       HANDLER el0_error_64                    // Error 64-bit EL0
+
+       HANDLER el0_sync_32                     // Synchronous 32-bit EL0
+       HANDLER el0_irq_32                      // IRQ 32-bit EL0
+       HANDLER el0_fiq_32                      // FIQ 32-bit EL0
+       HANDLER el0_error_32                    // Error 32-bit EL0
index cee92d477dc0cd42aa97a68cac9f3248e5d3883b..48b55c93f8582c9565e8c3d6cf0d64dde0fb7884 100644 (file)
@@ -6,6 +6,7 @@
  */
 
 #include <linux/compiler.h>
+#include <assert.h>
 
 #include "kvm_util.h"
 #include "../kvm_util_internal.h"
@@ -14,6 +15,8 @@
 #define KVM_GUEST_PAGE_TABLE_MIN_PADDR         0x180000
 #define DEFAULT_ARM64_GUEST_STACK_VADDR_MIN    0xac0000
 
+static vm_vaddr_t exception_handlers;
+
 static uint64_t page_align(struct kvm_vm *vm, uint64_t v)
 {
        return (v + vm->page_size) & ~(vm->page_size - 1);
@@ -334,6 +337,100 @@ void vcpu_args_set(struct kvm_vm *vm, uint32_t vcpuid, unsigned int num, ...)
        va_end(ap);
 }
 
+void kvm_exit_unexpected_exception(int vector, uint64_t ec, bool valid_ec)
+{
+       ucall(UCALL_UNHANDLED, 3, vector, ec, valid_ec);
+       while (1)
+               ;
+}
+
 void assert_on_unhandled_exception(struct kvm_vm *vm, uint32_t vcpuid)
 {
+       struct ucall uc;
+
+       if (get_ucall(vm, vcpuid, &uc) != UCALL_UNHANDLED)
+               return;
+
+       if (uc.args[2]) /* valid_ec */ {
+               assert(VECTOR_IS_SYNC(uc.args[0]));
+               TEST_FAIL("Unexpected exception (vector:0x%lx, ec:0x%lx)",
+                         uc.args[0], uc.args[1]);
+       } else {
+               assert(!VECTOR_IS_SYNC(uc.args[0]));
+               TEST_FAIL("Unexpected exception (vector:0x%lx)",
+                         uc.args[0]);
+       }
+}
+
+struct handlers {
+       handler_fn exception_handlers[VECTOR_NUM][ESR_EC_NUM];
+};
+
+void vcpu_init_descriptor_tables(struct kvm_vm *vm, uint32_t vcpuid)
+{
+       extern char vectors;
+
+       set_reg(vm, vcpuid, ARM64_SYS_REG(VBAR_EL1), (uint64_t)&vectors);
+}
+
+void route_exception(struct ex_regs *regs, int vector)
+{
+       struct handlers *handlers = (struct handlers *)exception_handlers;
+       bool valid_ec;
+       int ec = 0;
+
+       switch (vector) {
+       case VECTOR_SYNC_CURRENT:
+       case VECTOR_SYNC_LOWER_64:
+               ec = (read_sysreg(esr_el1) >> ESR_EC_SHIFT) & ESR_EC_MASK;
+               valid_ec = true;
+               break;
+       case VECTOR_IRQ_CURRENT:
+       case VECTOR_IRQ_LOWER_64:
+       case VECTOR_FIQ_CURRENT:
+       case VECTOR_FIQ_LOWER_64:
+       case VECTOR_ERROR_CURRENT:
+       case VECTOR_ERROR_LOWER_64:
+               ec = 0;
+               valid_ec = false;
+               break;
+       default:
+               valid_ec = false;
+               goto unexpected_exception;
+       }
+
+       if (handlers && handlers->exception_handlers[vector][ec])
+               return handlers->exception_handlers[vector][ec](regs);
+
+unexpected_exception:
+       kvm_exit_unexpected_exception(vector, ec, valid_ec);
+}
+
+void vm_init_descriptor_tables(struct kvm_vm *vm)
+{
+       vm->handlers = vm_vaddr_alloc(vm, sizeof(struct handlers),
+                       vm->page_size, 0, 0);
+
+       *(vm_vaddr_t *)addr_gva2hva(vm, (vm_vaddr_t)(&exception_handlers)) = vm->handlers;
+}
+
+void vm_install_sync_handler(struct kvm_vm *vm, int vector, int ec,
+                        void (*handler)(struct ex_regs *))
+{
+       struct handlers *handlers = addr_gva2hva(vm, vm->handlers);
+
+       assert(VECTOR_IS_SYNC(vector));
+       assert(vector < VECTOR_NUM);
+       assert(ec < ESR_EC_NUM);
+       handlers->exception_handlers[vector][ec] = handler;
+}
+
+void vm_install_exception_handler(struct kvm_vm *vm, int vector,
+                        void (*handler)(struct ex_regs *))
+{
+       struct handlers *handlers = addr_gva2hva(vm, vm->handlers);
+
+       assert(!VECTOR_IS_SYNC(vector));
+       assert(vector < VECTOR_NUM);
+       handlers->exception_handlers[vector][0] = handler;
 }
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