On Thu, May 06, 2021 at 02:30:17PM +0200, Auger Eric wrote:
> Hi Ricardo,
>
Hi Eric,
Thank you very much for the test.
> On 5/3/21 9:12 PM, Ricardo Koller wrote:
> > On Mon, May 03, 2021 at 11:32:39AM +0100, Marc Zyngier wrote:
> >> On Sat, 01 May 2021 00:24:06 +0100,
> >> Ricardo Koller <ricarkol@xxxxxxxxxx> wrote:
> >>>
> >>> 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_vector_handler(vector) or
> >>> vm_install_exception_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 heavily inspired on kvm-unit-tests.
>
> running the test on 5.12 I get
>
> ==== Test Assertion Failure ====
> aarch64/debug-exceptions.c:232: false
> pid=6477 tid=6477 errno=4 - Interrupted system call
> 1 0x000000000040147b: main at debug-exceptions.c:230
> 2 0x000003ff8aa60de3: ?? ??:0
> 3 0x0000000000401517: _start at :?
> Failed guest assert: hw_bp_addr == PC(hw_bp) at
> aarch64/debug-exceptions.c:105
> values: 0, 0x401794
>
>
> I guess it is not an expected result. Any known bug waiting on the list?
>
Not expected. That should work, or at least abort early because there is
no HW breakpoints support.
I'm trying to reproduce the failure; can you help me with some
questions, please?
- does your setup have support for hardware breakpoints? Can you try a
'dmesg | grep break'? I'm looking for something like 'hw-breakpoint:
found ...'. If there is no such line it's very likely that the check
for "debug_ver >= 6" is not enough and the test should check for
"num_breakpoints > 0".
- does it fail consistently (every single attempt)?
Thanks!
Ricardo
>
> Thanks
>
> Eric
> >>>
> >>> Signed-off-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
> >>> ---
> >>> tools/testing/selftests/kvm/Makefile | 2 +-
> >>> .../selftests/kvm/include/aarch64/processor.h | 78 +++++++++++
> >>> .../selftests/kvm/lib/aarch64/handlers.S | 130 ++++++++++++++++++
> >>> .../selftests/kvm/lib/aarch64/processor.c | 124 +++++++++++++++++
> >>> 4 files changed, 333 insertions(+), 1 deletion(-)
> >>> create mode 100644 tools/testing/selftests/kvm/lib/aarch64/handlers.S
> >>>
> >>> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> >>> index 4e548d7ab0ab..618c5903f478 100644
> >>> --- a/tools/testing/selftests/kvm/Makefile
> >>> +++ b/tools/testing/selftests/kvm/Makefile
> >>> @@ -35,7 +35,7 @@ endif
> >>>
> >>> LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.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
> >>> diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h b/tools/testing/selftests/kvm/include/aarch64/processor.h
> >>> index b7fa0c8551db..40aae31b4afc 100644
> >>> --- a/tools/testing/selftests/kvm/include/aarch64/processor.h
> >>> +++ b/tools/testing/selftests/kvm/include/aarch64/processor.h
> >>> @@ -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 +58,80 @@ 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)
> >>> +
> >>> +/* Some common EC (Exception classes) */
> >>> +#define ESR_EC_ILLEGAL_INS 0x0e
> >>> +#define ESR_EC_SVC64 0x15
> >>> +#define ESR_EC_IABORT_CURRENT 0x21
> >>> +#define ESR_EC_DABORT_CURRENT 0x25
> >>> +#define ESR_EC_SERROR 0x2f
> >>> +#define ESR_EC_HW_BP_CURRENT 0x31
> >>> +#define ESR_EC_SSTEP_CURRENT 0x33
> >>> +#define ESR_EC_WP_CURRENT 0x35
> >>> +#define ESR_EC_BRK_INS 0x3C
> >>> +
> >>> +#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, int ec, handler_fn handler);
> >>> +void vm_install_vector_handler(struct kvm_vm *vm,
> >>> + int vector, handler_fn handler);
> >>> +
> >>> +#define SPSR_D (1 << 9)
> >>> +#define SPSR_SS (1 << 21)
> >>> +
> >>> +#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
> >>> index 000000000000..8a560021892b
> >>> --- /dev/null
> >>> +++ b/tools/testing/selftests/kvm/lib/aarch64/handlers.S
> >>> @@ -0,0 +1,130 @@
> >>> +/* SPDX-License-Identifier: GPL-2.0 */
> >>> +.macro save_registers, vector
> >>> + 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]
> >>> +
> >>> + .if \vector >= 8
> >>> + mrs x1, sp_el0
> >>
> >> I'm still a bit perplexed by this. SP_EL0 is never changed, since you
> >> always run in handler mode. Therefore, saving/restoring it is only
> >> overhead. If an exception handler wants to introspect it, it is
> >> already available in the relevant system register.
> >>
> >> Or did you have something else in mind for it?
> >>
> >
> > Not really. The reason for saving sp_el0 in there was just for
> > consistency, so that handlers for both el0 and el1 exceptions could get
> > the sp at regs->sp.
> >
> > Restoring sp_el0 might be too much. So, what do you think of this v3: we
> > keep the saving of sp_el0 into regs->sp (to keep things the same between
> > el0 and el1) and delete the restoring of sp_el0?
> >
> > Thanks,
> > Ricardo
> >
> >>> + .else
> >>> + /*
> >>> + * This stores sp_el1 into ex_regs.sp so exception handlers can
> >>> + * "look" at it. It will _not_ be used to restore the sp_el1 on
> >>> + * return from the exception so handlers can not update it.
> >>> + */
> >>> + mov x1, sp
> >>> + .endif
> >>> + 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, vector
> >>> + ldp x1, x2, [sp, #16 * 16] /* PC, PSTATE */
> >>> + msr elr_el1, x1
> >>> + msr spsr_el1, x2
> >>> +
> >>> + ldp x30, x1, [sp, #16 * 15] /* x30, SP */
> >>> + .if \vector >= 8
> >>> + msr sp_el0, x1
> >>> + .endif
> >>> +
> >>> + 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 vector
> >>> + mov x0, sp
> >>> + mov x1, #vector
> >>> + bl route_exception
> >>> + restore_registers vector
> >>> +
> >>> +.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
> >>> + b kvm_exit_unexpected_vector
> >>> +.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
> >>> diff --git a/tools/testing/selftests/kvm/lib/aarch64/processor.c b/tools/testing/selftests/kvm/lib/aarch64/processor.c
> >>> index cee92d477dc0..25be71ec88be 100644
> >>> --- a/tools/testing/selftests/kvm/lib/aarch64/processor.c
> >>> +++ b/tools/testing/selftests/kvm/lib/aarch64/processor.c
> >>> @@ -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
> >>>
> >>> +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 +337,127 @@ void vcpu_args_set(struct kvm_vm *vm, uint32_t vcpuid, unsigned int num, ...)
> >>> va_end(ap);
> >>> }
> >>>
> >>> +void kvm_exit_unexpected_vector(int vector)
> >>> +{
> >>> + ucall(UCALL_UNHANDLED, 3, vector, 0, false /* !valid_ec */);
> >>> +}
> >>> +
> >>> +void kvm_exit_unexpected_exception(int vector, uint64_t ec)
> >>> +{
> >>> + ucall(UCALL_UNHANDLED, 3, vector, ec, true /* valid_ec */);
> >>> +}
> >>> +
> >>> 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_ASSERT(false,
> >>> + "Unexpected exception (vector:0x%lx, ec:0x%lx)",
> >>> + uc.args[0], uc.args[1]);
> >>> + } else {
> >>> + assert(!VECTOR_IS_SYNC(uc.args[0]));
> >>> + TEST_ASSERT(false,
> >>> + "Unexpected exception (vector:0x%lx)",
> >>> + uc.args[0]);
> >>> + }
> >>> +}
> >>> +
> >>> +/*
> >>> + * 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];
> >>> +};
> >>> +
> >>> +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 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);
> >>> +}
> >>> +
> >>> +void default_irq_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;
> >>> +
> >>> + if (handlers && handlers->vector_handlers[vector])
> >>> + handlers->vector_handlers[vector](regs, vector);
> >>> + else
> >>> + kvm_exit_unexpected_vector(vector);
> >>> +}
> >>> +
> >>> +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_irq_handler;
> >>> + handlers->vector_handlers[VECTOR_SYNC_LOWER_64] = default_sync_handler;
> >>> + handlers->vector_handlers[VECTOR_IRQ_LOWER_64] = default_irq_handler;
> >>
> >> How about FIQ, Error? Although they are unlikely, they are valid
> >> exceptions.
> >>
> >>> +
> >>> + *(vm_vaddr_t *)addr_gva2hva(vm, (vm_vaddr_t)(&exception_handlers)) = vm->handlers;
> >>> +}
> >>> +
> >>> +void vm_install_exception_handler(struct kvm_vm *vm, int vector, int ec,
> >>> + void (*handler)(struct ex_regs *))
> >>> +{
> >>> + struct handlers *handlers = (struct 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_vector_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;
> >>> }
> >>
> >> Thanks,
> >>
> >> M.
> >>
> >> --
> >> Without deviation from the norm, progress is not possible.
> >
>
