On Fri, Jun 04, 2021, Ricardo Koller wrote:
> Kernel test robot reports this:
>
> > /usr/bin/ld: tools/testing/selftests/kvm/x86_64/evmcs_test.c:157: undefined reference to `vm_handle_exception'
> > /usr/bin/ld: tools/testing/selftests/kvm/x86_64/evmcs_test.c:158: undefined reference to `vm_handle_exception'
> > collect2: error: ld returned 1 exit status
>
> Fix it by renaming vm_handle_exception to vm_install_vector_handler in
> evmcs_test.c.
>
> Fixes: a2bad6a990a4 ("KVM: selftests: Rename vm_handle_exception")
Belated code review... Can we rename the helper to vm_install_exception_handler()?
In x86, "vector" is the number of the exception and "vectoring" is the process
of determining the resulting vector that gets delivered to software (e.g. when
dealing with contributory faults like #GP->#PF->#DF), but the thing that's being
handled is an exception.
arm appears to have similar terminology. And looking at the arm code, it's very
confusing to have a helper vm_install_vector_handler() install into
exception_handlers, _not_ into vector_handlers. Calling the vector_handlers
"default" handlers is also confusing, as "default" usually implies the thing can
be overwritten. But in this case, the "default" handler is just another layer
in the routing.
The multiple layers of routing is also confusing and a bit hard to wade through
for the uninitiated. The whole thing can be made more straightfoward by doing
away with the intermediate routing, whacking ~50 lines of code in the process.
E.g. (definitely not functional code):
diff --git a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
index 51c42ac24dca..c784e4b770cf 100644
--- a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
+++ b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
@@ -212,15 +212,15 @@ int main(int argc, char *argv[])
exit(KSFT_SKIP);
}
- vm_install_exception_handler(vm, VECTOR_SYNC_CURRENT,
+ vm_install_exception_handler_ec(vm, VECTOR_SYNC_CURRENT,
ESR_EC_BRK_INS, guest_sw_bp_handler);
- vm_install_exception_handler(vm, VECTOR_SYNC_CURRENT,
+ vm_install_exception_handler_ec(vm, VECTOR_SYNC_CURRENT,
ESR_EC_HW_BP_CURRENT, guest_hw_bp_handler);
- vm_install_exception_handler(vm, VECTOR_SYNC_CURRENT,
+ vm_install_exception_handler_ec(vm, VECTOR_SYNC_CURRENT,
ESR_EC_WP_CURRENT, guest_wp_handler);
- vm_install_exception_handler(vm, VECTOR_SYNC_CURRENT,
+ vm_install_exception_handler_ec(vm, VECTOR_SYNC_CURRENT,
ESR_EC_SSTEP_CURRENT, guest_ss_handler);
- vm_install_exception_handler(vm, VECTOR_SYNC_CURRENT,
+ vm_install_exception_handler_ec(vm, VECTOR_SYNC_CURRENT,
ESR_EC_SVC64, guest_svc_handler);
for (stage = 0; stage < 7; stage++) {
diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h b/tools/testing/selftests/kvm/include/aarch64/processor.h
index 1a3abe1037b0..211cb684577a 100644
--- a/tools/testing/selftests/kvm/include/aarch64/processor.h
+++ b/tools/testing/selftests/kvm/include/aarch64/processor.h
@@ -110,10 +110,10 @@ 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, int ec, handler_fn handler);
-void vm_install_vector_handler(struct kvm_vm *vm,
- int vector, handler_fn handler);
+void vm_install_exception_handler_ec(struct kvm_vm *vm, int vector, int ec,
+ handler_fn handler);
+void vm_install_exception_handler(struct kvm_vm *vm, int vector,
+ handler_fn handler);
#define write_sysreg(reg, val) \
({ \
diff --git a/tools/testing/selftests/kvm/lib/aarch64/handlers.S b/tools/testing/selftests/kvm/lib/aarch64/handlers.S
index 49bf8827c6ab..fee0c3155ec7 100644
--- a/tools/testing/selftests/kvm/lib/aarch64/handlers.S
+++ b/tools/testing/selftests/kvm/lib/aarch64/handlers.S
@@ -93,7 +93,8 @@ handler_\label:
.balign 0x80
/* This will abort so no need to save and restore registers. */
mov x0, #vector
- b kvm_exit_unexpected_vector
+ <sean doesn't know what goes here>
+ b kvm_exit_unexpected_exception
.popsection
.set vector, vector + 1
diff --git a/tools/testing/selftests/kvm/lib/aarch64/processor.c b/tools/testing/selftests/kvm/lib/aarch64/processor.c
index 03ce507d49d2..ff63e66e2c5d 100644
--- a/tools/testing/selftests/kvm/lib/aarch64/processor.c
+++ b/tools/testing/selftests/kvm/lib/aarch64/processor.c
@@ -337,16 +337,9 @@ void vcpu_args_set(struct kvm_vm *vm, uint32_t vcpuid, unsigned int num, ...)
va_end(ap);
}
-void kvm_exit_unexpected_vector(int vector)
+void kvm_exit_unexpected_exception(int vector, uint64_t ec, bool valid_ec)
{
- ucall(UCALL_UNHANDLED, 3, vector, 0, false /* !valid_ec */);
- while (1)
- ;
-}
-
-static void kvm_exit_unexpected_exception(int vector, uint64_t ec)
-{
- ucall(UCALL_UNHANDLED, 3, vector, ec, true /* valid_ec */);
+ ucall(UCALL_UNHANDLED, 3, vector, ec, valid_ec);
while (1)
;
}
@@ -369,18 +362,7 @@ void assert_on_unhandled_exception(struct kvm_vm *vm, uint32_t vcpuid)
}
}
-/*
- * This exception handling code was heavily inspired on kvm-unit-tests. There
- * is a set of default vector handlers stored in vector_handlers. These default
- * vector handlers call user-installed handlers stored in exception_handlers.
- * Synchronous handlers are indexed by (vector, ec), and irq handlers by
- * (vector, ec=0).
- */
-
-typedef void(*vector_fn)(struct ex_regs *, int vector);
-
struct handlers {
- vector_fn vector_handlers[VECTOR_NUM];
handler_fn exception_handlers[VECTOR_NUM][ESR_EC_NUM];
};
@@ -391,80 +373,56 @@ void vcpu_init_descriptor_tables(struct kvm_vm *vm, uint32_t vcpuid)
set_reg(vm, vcpuid, ARM64_SYS_REG(VBAR_EL1), (uint64_t)&vectors);
}
-static void default_sync_handler(struct ex_regs *regs, int vector)
-{
- struct handlers *handlers = (struct handlers *)exception_handlers;
- uint64_t esr = read_sysreg(esr_el1);
- uint64_t ec = (esr >> ESR_EC_SHIFT) & ESR_EC_MASK;
-
- GUEST_ASSERT(VECTOR_IS_SYNC(vector));
-
- if (handlers && handlers->exception_handlers[vector][ec])
- handlers->exception_handlers[vector][ec](regs);
- else
- kvm_exit_unexpected_exception(vector, ec);
-}
-
-static void default_handler(struct ex_regs *regs, int vector)
-{
- struct handlers *handlers = (struct handlers *)exception_handlers;
-
- GUEST_ASSERT(!VECTOR_IS_SYNC(vector));
-
- if (handlers && handlers->exception_handlers[vector][0])
- handlers->exception_handlers[vector][0](regs);
- else
- kvm_exit_unexpected_vector(vector);
-}
-
void route_exception(struct ex_regs *regs, int vector)
{
- struct handlers *handlers = (struct handlers *)exception_handlers;
+ struct handler_fn *handlers = exception_handlers;
+ bool valid_ec;
+ int ec;
- if (handlers && handlers->vector_handlers[vector])
- handlers->vector_handlers[vector](regs, vector);
- else
- kvm_exit_unexpected_vector(vector);
+ 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:
+ goto unexpected_exception;
+ }
+
+ if (handlers && handlers[vector][ec])
+ return handlers[vector][ec](regs);
+
+unexpected_exception:
+ kvm_exit_unexpected_exception(vector, ec, valid_ec);
}
void vm_init_descriptor_tables(struct kvm_vm *vm)
{
- struct handlers *handlers;
-
- vm->handlers = vm_vaddr_alloc(vm, sizeof(struct handlers),
- vm->page_size, 0, 0);
-
- handlers = (struct handlers *)addr_gva2hva(vm, vm->handlers);
- handlers->vector_handlers[VECTOR_SYNC_CURRENT] = default_sync_handler;
- handlers->vector_handlers[VECTOR_IRQ_CURRENT] = default_handler;
- handlers->vector_handlers[VECTOR_FIQ_CURRENT] = default_handler;
- handlers->vector_handlers[VECTOR_ERROR_CURRENT] = default_handler;
-
- handlers->vector_handlers[VECTOR_SYNC_LOWER_64] = default_sync_handler;
- handlers->vector_handlers[VECTOR_IRQ_LOWER_64] = default_handler;
- handlers->vector_handlers[VECTOR_FIQ_LOWER_64] = default_handler;
- handlers->vector_handlers[VECTOR_ERROR_LOWER_64] = default_handler;
-
- *(vm_vaddr_t *)addr_gva2hva(vm, (vm_vaddr_t)(&exception_handlers)) = vm->handlers;
+ *(vm_vaddr_t *)addr_gva2hva(vm, (vm_vaddr_t)(&exception_handlers)) = __exception_handlers;
}
-void vm_install_exception_handler(struct kvm_vm *vm, int vector, int ec,
- void (*handler)(struct ex_regs *))
+void vm_install_exception_handler_ec(struct kvm_vm *vm, int vector, int ec,
+ void (*handler)(struct ex_regs *))
{
- struct handlers *handlers = (struct handlers *)addr_gva2hva(vm, vm->handlers);
+ struct handlers *handlers = addr_gva2hva(vm, vm->handlers);
- assert(VECTOR_IS_SYNC(vector));
+ assert(!ec == !VECTOR_IS_SYNC(vector));
assert(vector < VECTOR_NUM);
assert(ec < ESR_EC_NUM);
- handlers->exception_handlers[vector][ec] = handler;
+ exception_handlers[vector][ec] = handler;
}
-void vm_install_vector_handler(struct kvm_vm *vm, int vector,
- void (*handler)(struct ex_regs *))
+void vm_install_exception_handler(struct kvm_vm *vm, int vector,
+ void (*handler)(struct ex_regs *))
{
- struct handlers *handlers = (struct handlers *)addr_gva2hva(vm, vm->handlers);
-
- assert(!VECTOR_IS_SYNC(vector));
- assert(vector < VECTOR_NUM);
- handlers->exception_handlers[vector][0] = handler;
+ vm_install_exception_handler_ec(vm, vector, 0, handler);
}
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