On 12/9/25 09:04, Jim MacArthur wrote:
On 12/5/25 15:30, Richard Henderson wrote:
On 12/4/25 12:04, Jim MacArthur wrote:
@@ -6121,8 +6131,16 @@ static void tcr2_el2_write(CPUARMState *env, const ARMCPRegInfo
*ri,
if (cpu_isar_feature(aa64_mec, cpu)) {
valid_mask |= TCR2_AMEC0 | TCR2_AMEC1;
}
+ if (cpu_isar_feature(aa64_asid2, cpu)) {
+ valid_mask |= TCR2_FNG1 | TCR2_FNG0 | TCR2_A2;
+ require_flush = true;
+ }
value &= valid_mask;
raw_write(env, ri, value);
+
+ if (require_flush) {
+ tlb_flush(CPU(cpu));
+ }
Just because A2 is valid doesn't mean the A2 bit changed.
Compare, for instance, vmsa_ttbr_write, where we notice if the ASID has changed before
performing the flush.
Note as well that we don't need to flush all tlbs. In tcr2_el1_write we know that we
are only affecting the EL1&0 regime (alle1_tlbmask). In tcr2_el2_write, we know that we
are only affecting the EL2&0 regime (see the E2H part of vae2_tlbmask).
r~
Before I make a full patch series, can I check this looks correct?
In tcr2_el1_write:
if (cpu_isar_feature(aa64_asid2, cpu)) {
uint64_t asid_nonglobal_flags = TCR2_FNG1 | TCR2_FNG0 | TCR2_A2;
valid_mask |= asid_nonglobal_flags;
require_flush = ((raw_read(env, ri) ^ value) & asid_nonglobal_flags)
!= 0;
}
value &= valid_mask;
raw_write(env, ri, value);
if (require_flush) {
tlb_flush_by_mmuidx(CPU(cpu), alle1_tlbmask(env));
}
And then in tcr_el2_write, the same check but flushing by: ARMMMUIdxBit_E20_2 |
ARMMMUIdxBit_E20_2_PAN | ARMMMUIdxBit_E20_2_GCS | ARMMMUIdxBit_E20_0 |
ARMMMUIdxBit_E20_0_GCS, as used in vmsa_tcr_ttbr_el2_write. This could be factored out
into a constant function like alle1_tlbmask.
You don't actually need the require_flush boolean. You could just as well perform the
flush immediately -- there's nothing about tlb_flush that requires the raw_write to happen
first.
The FNG[01] bits don't affect ASID selection, so you don't need to flush when they change,
only when the A2 bit changes.
r~
