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| author | Sean Christopherson <seanjc@google.com> | 2022-11-19 01:34:44 +0000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-12-02 13:22:31 -0500 |
| commit | ef16b2dff4d1c71eb32b306d400d4c0f3a383ba7 (patch) | |
| tree | 8209f55b3709730fd025e0a26613f1764d64f14f | |
| parent | ef40757743b47cc95de9b4ed41525c94f8dc73d9 (diff) | |
| download | linux-ef16b2dff4d1c71eb32b306d400d4c0f3a383ba7.tar.bz2 | |
KVM: arm64: selftests: Enable single-step without a "full" ucall()
Add a new ucall hook, GUEST_UCALL_NONE(), to allow tests to make ucalls
without allocating a ucall struct, and use it to enable single-step
in ARM's debug-exceptions test. Like the disable single-step path, the
enabling path also needs to ensure that no exclusive access sequences are
attempted after enabling single-step, as the exclusive monitor is cleared
on ERET from the debug exception taken to EL2.
The test currently "works" because clear_bit() isn't actually an atomic
operation... yet.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221119013450.2643007-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | tools/testing/selftests/kvm/aarch64/debug-exceptions.c | 21 | ||||
| -rw-r--r-- | tools/testing/selftests/kvm/include/ucall_common.h | 8 |
2 files changed, 19 insertions, 10 deletions
diff --git a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c index d86c4e4d1c82..c62ec4d7f6a3 100644 --- a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c +++ b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c @@ -239,10 +239,6 @@ static void guest_svc_handler(struct ex_regs *regs) svc_addr = regs->pc; } -enum single_step_op { - SINGLE_STEP_ENABLE = 0, -}; - static void guest_code_ss(int test_cnt) { uint64_t i; @@ -253,8 +249,16 @@ static void guest_code_ss(int test_cnt) w_bvr = i << 2; w_wvr = i << 2; - /* Enable Single Step execution */ - GUEST_SYNC(SINGLE_STEP_ENABLE); + /* + * Enable Single Step execution. Note! This _must_ be a bare + * ucall as the ucall() path uses atomic operations to manage + * the ucall structures, and the built-in "atomics" are usually + * implemented via exclusive access instructions. The exlusive + * monitor is cleared on ERET, and so taking debug exceptions + * during a LDREX=>STREX sequence will prevent forward progress + * and hang the guest/test. + */ + GUEST_UCALL_NONE(); /* * The userspace will verify that the pc is as expected during @@ -356,12 +360,9 @@ void test_single_step_from_userspace(int test_cnt) break; } - TEST_ASSERT(cmd == UCALL_SYNC, + TEST_ASSERT(cmd == UCALL_NONE, "Unexpected ucall cmd 0x%lx", cmd); - TEST_ASSERT(uc.args[1] == SINGLE_STEP_ENABLE, - "Unexpected ucall action 0x%lx", uc.args[1]); - debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP; ss_enable = true; diff --git a/tools/testing/selftests/kvm/include/ucall_common.h b/tools/testing/selftests/kvm/include/ucall_common.h index bdd373189a77..1a6aaef5ccae 100644 --- a/tools/testing/selftests/kvm/include/ucall_common.h +++ b/tools/testing/selftests/kvm/include/ucall_common.h @@ -35,6 +35,14 @@ void ucall(uint64_t cmd, int nargs, ...); uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc); void ucall_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa); +/* + * Perform userspace call without any associated data. This bare call avoids + * allocating a ucall struct, which can be useful if the atomic operations in + * the full ucall() are problematic and/or unwanted. Note, this will come out + * as UCALL_NONE on the backend. + */ +#define GUEST_UCALL_NONE() ucall_arch_do_ucall((vm_vaddr_t)NULL) + #define GUEST_SYNC_ARGS(stage, arg1, arg2, arg3, arg4) \ ucall(UCALL_SYNC, 6, "hello", stage, arg1, arg2, arg3, arg4) #define GUEST_SYNC(stage) ucall(UCALL_SYNC, 2, "hello", stage) |