For consistency with the mte_check1 + mte_checkN merge
to mte_check, rename the probe function as well.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210416183106.1516563-8-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
The mte_check1 and mte_checkN functions are now identical.
Drop mte_check1 and rename mte_checkN to mte_check.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210416183106.1516563-7-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
After recent changes, mte_checkN does not use ESIZE,
and mte_check1 never used TSIZE. We can combine the
two into a single field: SIZEM1.
Choose to pass size - 1 because size == 0 is never used,
our immediate need in mte_probe_int is for the address
of the last byte (ptr + size - 1), and since almost all
operations are powers of 2, this makes the immediate
constant one bit smaller.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210416183106.1516563-6-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Add support for FEAT_SSBS. SSBS (Speculative Store Bypass Safe) is an
optional feature in ARMv8.0, and mandatory in ARMv8.5.
Signed-off-by: Rebecca Cran <rebecca@nuviainc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210216224543.16142-2-rebecca@nuviainc.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This also means we don't need an extra declaration of
the structure in hw/core/cpu.h.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210208233906.479571-2-richard.henderson@linaro.org>
Message-Id: <20210213130325.14781-11-alex.bennee@linaro.org>
Move everything related to syndromes to a new file,
which can be shared with linux-user.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20210212184902.1251044-26-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
We were fudging TBI1 enabled to speed up the generated code.
Now that we've improved the code generation, remove this.
Also, tidy the comment to reflect the current code.
The pauth test was testing a kernel address (-1) and making
incorrect assumptions about TBI1; stick to userland addresses.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210212184902.1251044-23-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Add support for FEAT_DIT. DIT (Data Independent Timing) is a required
feature for ARMv8.4. Since virtual machine execution is largely
nondeterministic and TCG is outside of the security domain, it's
implemented as a NOP.
Signed-off-by: Rebecca Cran <rebecca@nuviainc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210208065700.19454-2-rebecca@nuviainc.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
we cannot in principle make the TCG Operations field definitions
conditional on CONFIG_TCG in code that is included by both common_ss
and specific_ss modules.
Therefore, what we can do safely to restrict the TCG fields to TCG-only
builds, is to move all tcg cpu operations into a separate header file,
which is only included by TCG, target-specific code.
This leaves just a NULL pointer in the cpu.h for the non-TCG builds.
This also tidies up the code in all targets a bit, having all TCG cpu
operations neatly contained by a dedicated data struct.
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Message-Id: <20210204163931.7358-16-cfontana@suse.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
SVE predicate operations cannot use the "usual" simd_desc
encoding, because the lengths are not a multiple of 8.
But we were abusing the SIMD_* fields to store values anyway.
This abuse broke when SIMD_OPRSZ_BITS was modified in e2e7168a21.
Introduce a new set of field definitions for exclusive use
of predicates, so that it is obvious what kind of predicate
we are manipulating. To be used in future patches.
Cc: qemu-stable@nongnu.org
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210113062650.593824-2-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This adds the MMU indices for EL2 stage 1 in secure state.
To keep code contained, which is largelly identical between secure and
non-secure modes, the MMU indices are reassigned. The new assignments
provide a systematic pattern with a non-secure bit.
Signed-off-by: Rémi Denis-Courmont <remi.denis.courmont@huawei.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210112104511.36576-8-remi.denis.courmont@huawei.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Unlike many other bits in HCR_EL2, the description for this
bit does not contain the phrase "if ... this field behaves
as 0 for all purposes other than", so do not squash the bit
in arm_hcr_el2_eff.
Instead, replicate the E2H+TGE test in the two places that
require it.
Reported-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Message-id: 20201008162155.161886-4-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
We need to check the memattr of a page in order to determine
whether it is Tagged for MTE. Between Stage1 and Stage2,
this becomes simpler if we always collect this data, instead
of occasionally being presented with NULL.
Use the nonnull attribute to allow the compiler to check that
all pointer arguments are non-null.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-42-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Because the elements are sequential, we can eliminate many tests all
at once when the tag hits TCMA, or if the page(s) are not Tagged.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-34-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Fill out the stub that was added earlier.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-27-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Fill out the stub that was added earlier.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-26-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Replace existing uses of check_data_tbi in translate-a64.c that
perform a single logical memory access. Leave the helper blank
for now to reduce the patch size.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-24-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
We will shortly need this in mte_helper.c as well.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-23-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
We will shortly need this in mte_helper.c as well.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-22-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-12-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-10-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Cache the composite ATA setting.
Cache when MTE is fully enabled, i.e. access to tags are enabled
and tag checks affect the PE. Do this for both the normal context
and the UNPRIV context.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-9-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This is TFSRE0_EL1, TFSR_EL1, TFSR_EL2, TFSR_EL3,
RGSR_EL1, GCR_EL1, GMID_EL1, and PSTATE.TCO.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200626033144.790098-8-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Add a SIGBUS signal handler. In this handler, it checks the SIGBUS type,
translates the host VA delivered by host to guest PA, then fills this PA
to guest APEI GHES memory, then notifies guest according to the SIGBUS
type.
When guest accesses the poisoned memory, it will generate a Synchronous
External Abort(SEA). Then host kernel gets an APEI notification and calls
memory_failure() to unmapped the affected page in stage 2, finally
returns to guest.
Guest continues to access the PG_hwpoison page, it will trap to KVM as
stage2 fault, then a SIGBUS_MCEERR_AR synchronous signal is delivered to
Qemu, Qemu records this error address into guest APEI GHES memory and
notifes guest using Synchronous-External-Abort(SEA).
In order to inject a vSEA, we introduce the kvm_inject_arm_sea() function
in which we can setup the type of exception and the syndrome information.
When switching to guest, the target vcpu will jump to the synchronous
external abort vector table entry.
The ESR_ELx.DFSC is set to synchronous external abort(0x10), and the
ESR_ELx.FnV is set to not valid(0x1), which will tell guest that FAR is
not valid and hold an UNKNOWN value. These values will be set to KVM
register structures through KVM_SET_ONE_REG IOCTL.
Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
Signed-off-by: Xiang Zheng <zhengxiang9@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Xiang Zheng <zhengxiang9@huawei.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-id: 20200512030609.19593-10-gengdongjiu@huawei.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
None of the sve helpers use TCGMemOpIdx any longer, so we can
stop passing it.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200508154359.7494-20-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
If by context we know that we're in AArch64 mode, we need not
test for M-profile when reconstructing the full ARMMMUIdx.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20200302175829.2183-4-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
We're going to want to read the DBGDIDR register from KVM in
a subsequent commit, which means it needs to be in the
ARMISARegisters sub-struct. Move it.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200214175116.9164-12-peter.maydell@linaro.org
The AArch32 DBGDIDR defines properties like the number of
breakpoints, watchpoints and context-matching comparators. On an
AArch64 CPU, the register may not even exist if AArch32 is not
supported at EL1.
Currently we hard-code use of DBGDIDR to identify the number of
breakpoints etc; this works for all our TCG CPUs, but will break if
we ever add an AArch64-only CPU. We also have an assert() that the
AArch32 and AArch64 registers match, which currently works only by
luck for KVM because we don't populate either of these ID registers
from the KVM vCPU and so they are both zero.
Clean this up so we have functions for finding the number
of breakpoints, watchpoints and context comparators which look
in the appropriate ID register.
This allows us to drop the "check that AArch64 and AArch32 agree
on the number of breakpoints etc" asserts:
* we no longer look at the AArch32 versions unless that's the
right place to be looking
* it's valid to have a CPU (eg AArch64-only) where they don't match
* we shouldn't have been asserting the validity of ID registers
in a codepath used with KVM anyway
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200214175116.9164-11-peter.maydell@linaro.org
Enforce a convention that an isar_feature function that tests a
32-bit ID register always has _aa32_ in its name, and one that
tests a 64-bit ID register always has _aa64_ in its name.
We already follow this except for three cases: thumb_div,
arm_div and jazelle, which all need _aa32_ adding.
(As noted in the comment, isar_feature_aa32_fp16_arith()
is an exception in that it currently tests ID_AA64PFR0_EL1,
but will switch to MVFR1 once we've properly implemented
FP16 for AArch32.)
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20200214175116.9164-2-peter.maydell@linaro.org
For the purpose of rebuild_hflags_a64, we do not need to compute
all of the va parameters, only tbi. Moreover, we can compute them
in a form that is more useful to storing in hflags.
This eliminates the need for aa64_va_parameter_both, so fold that
in to aa64_va_parameter. The remaining calls to aa64_va_parameter
are in get_phys_addr_lpae and in pauth_helper.c.
This reduces the total cpu consumption of aa64_va_parameter in a
kernel boot plus a kvm guest kernel boot from 3% to 0.5%.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200216194343.21331-5-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200208125816.14954-19-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
If we have a PAN-enforcing mmu_idx, set prot == 0 if user_rw != 0.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200208125816.14954-14-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
For aarch64, there's a dedicated msr (imm, reg) insn.
For aarch32, this is done via msr to cpsr. Writes from el0
are ignored, which is already handled by the CPSR_USER mask.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200208125816.14954-12-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Use this along the exception return path, where we previously
accepted any values.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200208125816.14954-11-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
The J bit signals Jazelle mode, and so of course is RES0
when the feature is not enabled.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20200208125816.14954-7-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Split this helper out of msr_mask in translate.c. At the same time,
transform the negative reductive logic to positive accumulative logic.
It will be usable along the exception paths.
While touching msr_mask, fix up formatting.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20200208125816.14954-6-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
To implement PAN, we will want to swap, for short periods
of time, to a different privileged mmu_idx. In addition,
we cannot do this with flushing alone, because the AT*
instructions have both PAN and PAN-less versions.
Add the ARMMMUIdx*_PAN constants where necessary next to
the corresponding ARMMMUIdx* constant.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200208125816.14954-3-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Use a common predicate for querying stage1-ness.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200208125816.14954-2-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Create a predicate to indicate whether the regime has
both positive and negative addresses.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200206105448.4726-21-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Prepare for, but do not yet implement, the EL2&0 regime.
This involves adding the new MMUIdx enumerators and adjusting
some of the MMUIdx related predicates to match.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200206105448.4726-20-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This is part of a reorganization to the set of mmu_idx.
The non-secure EL2 regime only has a single stage translation;
there is no point in pointing out that the idx is for stage1.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200206105448.4726-15-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This is part of a reorganization to the set of mmu_idx.
The EL3 regime only has a single stage translation, and
is always secure.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200206105448.4726-14-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This is part of a reorganization to the set of mmu_idx.
This emphasizes that they apply to the Secure EL1&0 regime.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200206105448.4726-13-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This is part of a reorganization to the set of mmu_idx.
The EL1&0 regime is the only one that uses 2-stage translation.
Spelling out Stage avoids confusion with Secure.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200206105448.4726-12-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
The EL1&0 regime is the only one that uses 2-stage translation.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200206105448.4726-11-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This is part of a reorganization to the set of mmu_idx.
This emphasizes that they apply to the EL1&0 regime.
The ultimate goal is
-- Non-secure regimes:
ARMMMUIdx_E10_0,
ARMMMUIdx_E20_0,
ARMMMUIdx_E10_1,
ARMMMUIdx_E2,
ARMMMUIdx_E20_2,
-- Secure regimes:
ARMMMUIdx_SE10_0,
ARMMMUIdx_SE10_1,
ARMMMUIdx_SE3,
-- Helper mmu_idx for non-secure EL1&0 stage1 and stage2
ARMMMUIdx_Stage2,
ARMMMUIdx_Stage1_E0,
ARMMMUIdx_Stage1_E1,
The 'S' prefix is reserved for "Secure". Unless otherwise specified,
each mmu_idx represents all stages of translation.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200206105448.4726-10-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
In the next commit we will split the M-profile functions from this
file. Some function will be called out of helper.c. Declare them in
the "internals.h" header.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190701132516.26392-22-philmd@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
