diff options
| author | Zenghui Yu (Huawei) <zenghui.yu@linux.dev> | 2026-03-17 16:15:58 +0300 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2026-04-01 19:29:21 +0300 |
| commit | 03db5f05d4c76d76b32a9d26001e2ec6252f74f8 (patch) | |
| tree | bf3c71093f0d790fa2a5f9cb12f839cd8e2252cb /tools | |
| parent | a3ca3bfd01b7ee9f54ed85718a6d553cdd87050e (diff) | |
| download | linux-03db5f05d4c76d76b32a9d26001e2ec6252f74f8.tar.xz | |
KVM: arm64: selftests: Avoid testing the IMPDEF behavior
It turned out that we can't really force KVM to use the "slow" path when
emulating AT instructions [1]. We should therefore avoid testing the IMPDEF
behavior (i.e., TEST_ACCESS_FLAG - address translation instructions are
permitted to update AF but not required).
Remove it and improve the comment a bit.
[1] https://lore.kernel.org/r/b951dcfb-0ad1-4d7b-b6ce-d54b272dd9be@linux.dev
Signed-off-by: Zenghui Yu (Huawei) <zenghui.yu@linux.dev>
Link: https://patch.msgid.link/20260317131558.52751-1-zenghui.yu@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/kvm/arm64/at.c | 14 |
1 files changed, 2 insertions, 12 deletions
diff --git a/tools/testing/selftests/kvm/arm64/at.c b/tools/testing/selftests/kvm/arm64/at.c index c8ee6f520734..ce5d312ef6ba 100644 --- a/tools/testing/selftests/kvm/arm64/at.c +++ b/tools/testing/selftests/kvm/arm64/at.c @@ -13,7 +13,6 @@ enum { CLEAR_ACCESS_FLAG, - TEST_ACCESS_FLAG, }; static u64 *ptep_hva; @@ -49,7 +48,6 @@ do { \ GUEST_ASSERT_EQ(FIELD_GET(SYS_PAR_EL1_ATTR, par), MAIR_ATTR_NORMAL); \ GUEST_ASSERT_EQ(FIELD_GET(SYS_PAR_EL1_SH, par), PTE_SHARED >> 8); \ GUEST_ASSERT_EQ(par & SYS_PAR_EL1_PA, TEST_ADDR); \ - GUEST_SYNC(TEST_ACCESS_FLAG); \ } \ } while (0) @@ -85,10 +83,6 @@ static void guest_code(void) if (!SYS_FIELD_GET(ID_AA64MMFR1_EL1, HAFDBS, read_sysreg(id_aa64mmfr1_el1))) GUEST_DONE(); - /* - * KVM's software PTW makes the implementation choice that the AT - * instruction sets the access flag. - */ sysreg_clear_set(tcr_el1, 0, TCR_HA); isb(); test_at(false); @@ -102,8 +96,8 @@ static void handle_sync(struct kvm_vcpu *vcpu, struct ucall *uc) case CLEAR_ACCESS_FLAG: /* * Delete + reinstall the memslot to invalidate stage-2 - * mappings of the stage-1 page tables, forcing KVM to - * use the 'slow' AT emulation path. + * mappings of the stage-1 page tables, allowing KVM to + * potentially use the 'slow' AT emulation path. * * This and clearing the access flag from host userspace * ensures that the access flag cannot be set speculatively @@ -112,10 +106,6 @@ static void handle_sync(struct kvm_vcpu *vcpu, struct ucall *uc) clear_bit(__ffs(PTE_AF), ptep_hva); vm_mem_region_reload(vcpu->vm, vcpu->vm->memslots[MEM_REGION_PT]); break; - case TEST_ACCESS_FLAG: - TEST_ASSERT(test_bit(__ffs(PTE_AF), ptep_hva), - "Expected access flag to be set (desc: %lu)", *ptep_hva); - break; default: TEST_FAIL("Unexpected SYNC arg: %lu", uc->args[1]); } |