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| author | Sean Christopherson <seanjc@google.com> | 2022-11-17 00:23:50 +0000 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2022-11-16 16:58:14 -0800 |
| commit | b3d937722de0e64eebe267451a0e3d5ed5107ef7 (patch) | |
| tree | 3cdbb3d248ebdbfdf8e624fb70e780bb8f5a7218 | |
| parent | 1cec8bbc1764964de24d19983fbf9fee6ce3c09d (diff) | |
| download | linux-b3d937722de0e64eebe267451a0e3d5ed5107ef7.tar.bz2 | |
KVM: arm64: selftests: Disable single-step without relying on ucall()
Automatically disable single-step when the guest reaches the end of the
verified section instead of using an explicit ucall() to ask userspace to
disable single-step. An upcoming change to implement a pool-based scheme
for ucall() will add an atomic operation (bit test and set) in the guest
ucall code, and if the compiler generate "old school" atomics, e.g.
40e57c: c85f7c20 ldxr x0, [x1]
40e580: aa100011 orr x17, x0, x16
40e584: c80ffc31 stlxr w15, x17, [x1]
40e588: 35ffffaf cbnz w15, 40e57c <__aarch64_ldset8_sync+0x1c>
the guest will hang as the local exclusive monitor is reset by eret,
i.e. the stlxr will always fail due to the debug exception taken to EL2.
Link: https://lore.kernel.org/all/20221006003409.649993-8-seanjc@google.com
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221117002350.2178351-3-seanjc@google.com
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
| -rw-r--r-- | tools/testing/selftests/kvm/aarch64/debug-exceptions.c | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c index 0316f225d36a..a3c2216b65fb 100644 --- a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c +++ b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c @@ -241,7 +241,6 @@ static void guest_svc_handler(struct ex_regs *regs) enum single_step_op { SINGLE_STEP_ENABLE = 0, - SINGLE_STEP_DISABLE = 1, }; static void guest_code_ss(int test_cnt) @@ -258,7 +257,7 @@ static void guest_code_ss(int test_cnt) GUEST_SYNC(SINGLE_STEP_ENABLE); /* - * The userspace will veriry that the pc is as expected during + * The userspace will verify that the pc is as expected during * single step execution between iter_ss_begin and iter_ss_end. */ asm volatile("iter_ss_begin:nop\n"); @@ -268,11 +267,9 @@ static void guest_code_ss(int test_cnt) bvr = read_sysreg(dbgbvr0_el1); wvr = read_sysreg(dbgwvr0_el1); + /* Userspace disables Single Step when the end is nigh. */ asm volatile("iter_ss_end:\n"); - /* Disable Single Step execution */ - GUEST_SYNC(SINGLE_STEP_DISABLE); - GUEST_ASSERT(bvr == w_bvr); GUEST_ASSERT(wvr == w_wvr); } @@ -364,15 +361,12 @@ void test_single_step_from_userspace(int test_cnt) TEST_ASSERT(cmd == UCALL_SYNC, "Unexpected ucall cmd 0x%lx", cmd); - if (uc.args[1] == SINGLE_STEP_ENABLE) { - debug.control = KVM_GUESTDBG_ENABLE | - KVM_GUESTDBG_SINGLESTEP; - ss_enable = true; - } else { - debug.control = KVM_GUESTDBG_ENABLE; - ss_enable = false; - } + 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; vcpu_guest_debug_set(vcpu, &debug); continue; } @@ -385,6 +379,14 @@ void test_single_step_from_userspace(int test_cnt) "Unexpected pc 0x%lx (expected 0x%lx)", pc, test_pc); + if ((pc + 4) == (uint64_t)&iter_ss_end) { + test_pc = 0; + debug.control = KVM_GUESTDBG_ENABLE; + ss_enable = false; + vcpu_guest_debug_set(vcpu, &debug); + continue; + } + /* * If the current pc is between iter_ss_bgin and * iter_ss_end, the pc for the next KVM_EXIT_DEBUG should |