If translation is disabled, the default memory type is Device, which requires alignment checking. Document, but defer, the more general case of per-page alignment checking.
Reported-by: Idan Horowitz <idan.horow...@gmail.com> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1204 Signed-off-by: Richard Henderson <richard.hender...@linaro.org> --- target/arm/helper.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-) diff --git a/target/arm/helper.c b/target/arm/helper.c index d7bc467a2a..79609443aa 100644 --- a/target/arm/helper.c +++ b/target/arm/helper.c @@ -10713,6 +10713,39 @@ ARMMMUIdx arm_mmu_idx(CPUARMState *env) return arm_mmu_idx_el(env, arm_current_el(env)); } +/* + * Return true if memory alignment should be enforced. + */ +static bool aprofile_require_alignment(CPUARMState *env, int el, uint64_t sctlr) +{ + /* Check the alignment enable bit. */ + if (sctlr & SCTLR_A) { + return true; + } + + /* + * If translation is disabled, then the default memory type + * may be Device(-nGnRnE) instead of Normal, which requires that + * alignment be enforced. + * + * TODO: The more general case is translation enabled, with a per-page + * check of the memory type as assigned via MAIR_ELx and the PTE. + * We could arrange for a bit in MemTxAttrs to enforce alignment + * via forced use of the softmmu slow path. Given that such pages + * are intended for MMIO, where the slow path is required anyhow, + * this should not result in extra overhead. + */ + if (sctlr & SCTLR_M) { + /* Translation enabled: memory type in PTE via MAIR_ELx. */ + return false; + } + if (el < 2 && (arm_hcr_el2_eff(env) & (HCR_DC | HCR_VM))) { + /* Stage 2 translation enabled: memory type in PTE. */ + return false; + } + return true; +} + static CPUARMTBFlags rebuild_hflags_common(CPUARMState *env, int fp_el, ARMMMUIdx mmu_idx, CPUARMTBFlags flags) @@ -10777,8 +10810,9 @@ static CPUARMTBFlags rebuild_hflags_a32(CPUARMState *env, int fp_el, { CPUARMTBFlags flags = {}; int el = arm_current_el(env); + uint64_t sctlr = arm_sctlr(env, el); - if (arm_sctlr(env, el) & SCTLR_A) { + if (aprofile_require_alignment(env, el, sctlr)) { DP_TBFLAG_ANY(flags, ALIGN_MEM, 1); } @@ -10871,7 +10905,7 @@ static CPUARMTBFlags rebuild_hflags_a64(CPUARMState *env, int el, int fp_el, sctlr = regime_sctlr(env, stage1); - if (sctlr & SCTLR_A) { + if (aprofile_require_alignment(env, el, sctlr)) { DP_TBFLAG_ANY(flags, ALIGN_MEM, 1); } -- 2.34.1
