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The FEAT_DoubleFault extension adds the following:
* All external aborts on instruction fetches and translation table
walks for instruction fetches must be synchronous. For QEMU this
is already true.
* SCR_EL3 has a new bit NMEA which disables the masking of SError
interrupts by PSTATE.A when the SError interrupt is taken to EL3.
For QEMU we only need to make the bit writable, because we have no
sources of SError interrupts.
* SCR_EL3 has a new bit EASE which causes synchronous external
aborts taken to EL3 to be taken at the same entry point as SError.
(Note that this does not mean that they are SErrors for purposes
of PSTATE.A masking or that the syndrome register reports them as
SErrors: it just means that the vector offset is different.)
* The existing SCTLR_EL3.IESB has an effective value of 1 when
SCR_EL3.NMEA is 1. For QEMU this is a no-op because we don't need
different behaviour based on IESB (we don't need to do anything to
ensure that error exceptions are synchronized).
So for QEMU the things we need to change are:
* Make SCR_EL3.{NMEA,EASE} writable
* When taking a synchronous external abort at EL3, adjust the
vector entry point if SCR_EL3.EASE is set
* Advertise the feature in the ID registers
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220531151431.949322-1-peter.maydell@linaro.org
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The architectural feature RASv1p1 introduces the following new
features:
* new registers ERXPFGCDN_EL1, ERXPFGCTL_EL1 and ERXPFGF_EL1
* new bits in the fine-grained trap registers that control traps
for these new registers
* new trap bits HCR_EL2.FIEN and SCR_EL3.FIEN that control traps
for ERXPFGCDN_EL1, ERXPFGCTL_EL1, ERXPFGP_EL1
* a larger number of the ERXMISC<n>_EL1 registers
* the format of ERR<n>STATUS registers changes
The architecture permits that if ERRIDR_EL1.NUM is 0 (as it is for
QEMU) then all these new registers may UNDEF, and the HCR_EL2.FIEN
and SCR_EL3.FIEN bits may be RES0. We don't have any ERR<n>STATUS
registers (again, because ERRIDR_EL1.NUM is 0). QEMU does not yet
implement the fine-grained-trap extension. So there is nothing we
need to implement to be compliant with the feature spec. Make the
'max' CPU report the feature in its ID registers, and document it.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220531114258.855804-1-peter.maydell@linaro.org
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In commit 5814d587fe861fe9 we added support for emulating
FEAT_HCX (Support for the HCRX_EL2 register). However we
forgot to add it to the list in emulated.rst. Correct the
omission.
Fixes: 5814d587fe861fe9 ("target/arm: Enable FEAT_HCX for -cpu max")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220520084320.424166-1-peter.maydell@linaro.org
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The Armv8.4 feature FEAT_IDST specifies that exceptions generated by
read accesses to the feature ID space should report a syndrome code
of 0x18 (EC_SYSTEMREGISTERTRAP) rather than 0x00 (EC_UNCATEGORIZED).
The feature ID space is defined to be:
op0 == 3, op1 == {0,1,3}, CRn == 0, CRm == {0-7}, op2 == {0-7}
In our implementation we might return the EC_UNCATEGORIZED syndrome
value for a system register access in four cases:
* no reginfo struct in the hashtable
* cp_access_ok() fails (ie ri->access doesn't permit the access)
* ri->accessfn returns CP_ACCESS_TRAP_UNCATEGORIZED at runtime
* ri->type includes ARM_CP_RAISES_EXC, and the readfn raises
an UNDEF exception at runtime
We have very few regdefs that set ARM_CP_RAISES_EXC, and none of
them are in the feature ID space. (In the unlikely event that any
are added in future they would need to take care of setting the
correct syndrome themselves.) This patch deals with the other
three cases, and enables FEAT_IDST for AArch64 -cpu max.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220509155457.3560724-1-peter.maydell@linaro.org
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Enable the FEAT_S2FWB for -cpu max. Since FEAT_S2FWB requires that
CLIDR_EL1.{LoUU,LoUIS} are zero, we explicitly squash these (the
inherited CLIDR_EL1 value from the Cortex-A57 has them as 1).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220505183950.2781801-5-peter.maydell@linaro.org
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This extension concerns not merging memory access, which TCG does
not implement. Thus we can trivially enable this feature.
Add a comment to handle_hint for the DGH instruction, but no code.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220506180242.216785-23-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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This extension concerns cache speculation, which TCG does
not implement. Thus we can trivially enable this feature.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220506180242.216785-22-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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There is no branch prediction in TCG, therefore there is no
need to actually include the context number into the predictor.
Therefore all we need to do is add the state for SCXTNUM_ELx.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220506180242.216785-21-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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This extension concerns branch speculation, which TCG does
not implement. Thus we can trivially enable this feature.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220506180242.216785-20-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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This feature is AArch64 only, and applies to physical SErrors,
which QEMU does not implement, thus the feature is a nop.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220506180242.216785-19-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220506180242.216785-18-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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This extension concerns changes to the External Debug interface,
with Secure and Non-secure access to the debug registers, and all
of it is outside the scope of QEMU. Indicating support for this
is mandatory with FEAT_SEL2, which we do implement.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220506180242.216785-13-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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The only portion of FEAT_Debugv8p2 that is relevant to QEMU
is CONTEXTIDR_EL2, which is also conditionally implemented
with FEAT_VHE. The rest of the debug extension concerns the
External debug interface, which is outside the scope of QEMU.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220506180242.216785-12-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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The description in the Arm ARM of the requirements of FEAT_BBM is
admirably clear on the guarantees it provides software, but slightly
more obscure on what that means for implementations. The description
of the equivalent SMMU feature in the SMMU specification (IHI0070D.b
section 3.21.1) is perhaps a bit more detailed and includes some
example valid implementation choices. (The SMMU version of this
feature is slightly tighter than the CPU version: the CPU is permitted
to raise TLB Conflict aborts in some situations that the SMMU may
not. This doesn't matter for QEMU because we don't want to do TLB
Conflict aborts anyway.)
The informal summary of FEAT_BBM is that it is about permitting an OS
to switch a range of memory between "covered by a huge page" and
"covered by a sequence of normal pages" without having to engage in
the 'break-before-make' dance that has traditionally been
necessary. The 'break-before-make' sequence is:
* replace the old translation table entry with an invalid entry
* execute a DSB insn
* execute a broadcast TLB invalidate insn
* execute a DSB insn
* write the new translation table entry
* execute a DSB insn
The point of this is to ensure that no TLB can simultaneously contain
TLB entries for the old and the new entry, which would traditionally
be UNPREDICTABLE (allowing the CPU to generate a TLB Conflict fault
or to use a random mishmash of values from the old and the new
entry). FEAT_BBM level 2 says "for the specific case where the only
thing that changed is the size of the block, the TLB is guaranteed
not to do weird things even if there are multiple entries for an
address", which means that software can now do:
* replace old translation table entry with new entry
* DSB
* broadcast TLB invalidate
* DSB
As the SMMU spec notes, valid ways to do this include:
* if there are multiple entries in the TLB for an address,
choose one of them and use it, ignoring the others
* if there are multiple entries in the TLB for an address,
throw them all out and do a page table walk to get a new one
QEMU's page table walk implementation for Arm CPUs already meets the
requirements for FEAT_BBM level 2. When we cache an entry in our TCG
TLB, we do so only for the specific (non-huge) page that the address
is in, and there is no way for the TLB data structure to ever have
more than one TLB entry for that page. (We handle huge pages only in
that we track what part of the address space is covered by huge pages
so that a TLB invalidate operation for an address in a huge page
results in an invalidation of the whole TLB.) We ignore the Contiguous
bit in page table entries, so we don't have to do anything for the
parts of FEAT_BBM that deal with changis to the Contiguous bit.
FEAT_BBM level 2 also requires that the nT bit in block descriptors
must be ignored; since commit 39a1fd25287f5dece5 we do this.
It's therefore safe for QEMU to advertise FEAT_BBM level 2 by
setting ID_AA64MMFR2_EL1.BBM to 2.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220426160422.2353158-3-peter.maydell@linaro.org
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The Arm FEAT_TTL architectural feature allows the guest to provide an
optional hint in an AArch64 TLB invalidate operation about which
translation table level holds the leaf entry for the address being
invalidated. QEMU's TLB implementation doesn't need that hint, and
we correctly ignore the (previously RES0) bits in TLB invalidate
operation values that are now used for the TTL field. So we can
simply advertise support for it in our 'max' CPU.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220426160422.2353158-2-peter.maydell@linaro.org
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This feature widens physical addresses (and intermediate physical
addresses for 2-stage translation) from 48 to 52 bits, when using
4k or 16k pages.
This introduces the DS bit to TCR_ELx, which is RES0 unless the
page size is enabled and supports LPA2, resulting in the effective
value of DS for a given table walk. The DS bit changes the format
of the page table descriptor slightly, moving the PS field out to
TCR so that all pages have the same sharability and repurposing
those bits of the page table descriptor for the highest bits of
the output address.
Do not yet enable FEAT_LPA2; we need extra plumbing to avoid
tickling an old kernel bug.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220301215958.157011-17-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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This feature widens physical addresses (and intermediate physical
addresses for 2-stage translation) from 48 to 52 bits, when using
64k pages. The only thing left at this point is to handle the
extra bits in the TTBR and in the table descriptors.
Note that PAR_EL1 and HPFAR_EL2 are nominally extended, but we don't
mask out the high bits when writing to those registers, so no changes
are required there.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220301215958.157011-11-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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This feature is relatively small, as it applies only to
64k pages and thus requires no additional changes to the
table descriptor walking algorithm, only a change to the
minimum TSZ (which is the inverse of the maximum virtual
address space size).
Note that this feature widens VBAR_ELx, but we already
treat the register as being 64 bits wide.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220301215958.157011-10-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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MTE3 introduces an asymmetric tag checking mode, in which loads are
checked synchronously and stores are checked asynchronously. Add
support for it.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210616195614.11785-1-pcc@google.com
[PMM: Add line to emulation.rst]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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These days the Arm architecture has a wide range of fine-grained
optional extra architectural features. We implement quite a lot
of these but by no means all of them. Document what we do implement,
so that users can find out without having to dig through back-issues
of our Changelog on the wiki.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20210617140328.28622-1-peter.maydell@linaro.org
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
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