Commit Graph

108810 Commits

Author SHA1 Message Date
Rajnesh Kanwal
40336d5b1d target/riscv: Add HS-mode virtual interrupt and IRQ filtering support.
This change adds support for inserting virtual interrupts from HS-mode
into VS-mode using hvien and hvip csrs. This also allows for IRQ filtering
from HS-mode.

Also, the spec doesn't mandate the interrupt to be actually supported
in hardware. Which allows HS-mode to assert virtual interrupts to VS-mode
that have no connection to any real interrupt events.

This is defined as part of the AIA specification [0], "6.3.2 Virtual
interrupts for VS level".

[0]: https://github.com/riscv/riscv-aia/releases/download/1.0/riscv-interrupts-1.0.pdf

Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20231016111736.28721-7-rkanwal@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2023-11-07 11:02:17 +10:00
Rajnesh Kanwal
1697837ed9 target/riscv: Add M-mode virtual interrupt and IRQ filtering support.
This change adds support for inserting virtual interrupts from M-mode
into S-mode using mvien and mvip csrs. IRQ filtering is a use case of
this change, i-e M-mode can stop delegating an interrupt to S-mode and
instead enable it in MIE and receive those interrupts in M-mode and then
selectively inject the interrupt using mvien and mvip.

Also, the spec doesn't mandate the interrupt to be actually supported
in hardware. Which allows M-mode to assert virtual interrupts to S-mode
that have no connection to any real interrupt events.

This is defined as part of the AIA specification [0], "5.3 Interrupt
filtering and virtual interrupts for supervisor level".

[0]: https://github.com/riscv/riscv-aia/releases/download/1.0/riscv-interrupts-1.0.pdf

Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20231016111736.28721-6-rkanwal@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2023-11-07 11:02:17 +10:00
Rajnesh Kanwal
1ebad505f3 target/riscv: Split interrupt logic from riscv_cpu_update_mip.
This is to allow virtual interrupts to be inserted into S and VS
modes. Given virtual interrupts will be maintained in separate
mvip and hvip CSRs, riscv_cpu_update_mip will no longer be in the
path and interrupts need to be triggered for these cases from
rmw_hvip64 and rmw_mvip64 functions.

Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231016111736.28721-5-rkanwal@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2023-11-07 11:02:17 +10:00
Rajnesh Kanwal
b901c7eb70 target/riscv: Set VS* bits to one in mideleg when H-Ext is enabled
With H-Ext supported, VS bits are all hardwired to one in MIDELEG
denoting always delegated interrupts. This is being done in rmw_mideleg
but given mideleg is used in other places when routing interrupts
this change initializes it in riscv_cpu_realize to be on the safe side.

Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231016111736.28721-4-rkanwal@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2023-11-07 11:02:17 +10:00
Rajnesh Kanwal
d17bcae5f7 target/riscv: Check for async flag in case of RISCV_EXCP_SEMIHOST.
RISCV_EXCP_SEMIHOST is set to 0x10, which can be a local interrupt id
as well. This change moves RISCV_EXCP_SEMIHOST to switch case so that
async flag check is performed before invoking semihosting logic.

Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231016111736.28721-3-rkanwal@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2023-11-07 11:02:17 +10:00
Rajnesh Kanwal
a7b6917025 target/riscv: Without H-mode mask all HS mode inturrupts in mie.
Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231016111736.28721-2-rkanwal@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2023-11-07 11:02:17 +10:00
Daniel Henrique Barboza
e57039ddab target/riscv: rename ext_icboz to ext_zicboz
Add a leading 'z' to improve grepping. When one wants to search for uses
of zicboz they're more likely to do 'grep -i zicboz' than 'grep -i
icboz'.

Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Message-ID: <20231012164604.398496-5-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2023-11-07 11:02:17 +10:00
Daniel Henrique Barboza
a326a2b0b2 target/riscv: rename ext_icbom to ext_zicbom
Add a leading 'z' to improve grepping. When one wants to search for uses
of zicbom they're more likely to do 'grep -i zicbom' than 'grep -i
icbom'.

Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Message-ID: <20231012164604.398496-4-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2023-11-07 11:02:17 +10:00
Daniel Henrique Barboza
960b389b7d target/riscv: rename ext_icsr to ext_zicsr
Add a leading 'z' to improve grepping. When one wants to search for uses
of zicsr they're more likely to do 'grep -i zicsr' than 'grep -i icsr'.

Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Message-ID: <20231012164604.398496-3-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2023-11-07 11:02:17 +10:00
Daniel Henrique Barboza
12b12a14c7 target/riscv: rename ext_ifencei to ext_zifencei
Add a leading 'z' to improve grepping. When one wants to search for uses
of zifencei they're more likely to do 'grep -i zifencei' than 'grep -i
ifencei'.

Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Message-ID: <20231012164604.398496-2-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2023-11-07 11:02:17 +10:00
Richard Henderson
d36ce28be4 tcg/sparc64: Implement tcg_out_extrl_i64_i32
Build fix for missing symbol.

Cc: qemu-stable@nongnu.org
Fixes: dad2f2f5af ("tcg/sparc64: Disable TCG_TARGET_HAS_extr_i64_i32")
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-11-06 10:48:46 -08:00
Richard Henderson
f245757701 tcg/optimize: Canonicalize sub2 with constants to add2
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20231026013945.1152174-4-richard.henderson@linaro.org>
2023-11-06 10:43:04 -08:00
Richard Henderson
6334a968ee tcg/optimize: Canonicalize subi to addi during optimization
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20231026013945.1152174-3-richard.henderson@linaro.org>
2023-11-06 10:43:04 -08:00
Richard Henderson
1551004eeb tcg: Canonicalize subi to addi during opcode generation
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20231026013945.1152174-2-richard.henderson@linaro.org>
2023-11-06 10:43:04 -08:00
Richard Henderson
26aac97c84 tcg/optimize: Split out arg_new_constant
Fixes a bug wherein raw uses of tcg_constant_internal
do not have their TempOptInfo initialized.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-11-06 10:36:56 -08:00
Richard Henderson
3eaadaeb4e tcg: Eliminate duplicate env store operations
Notice when a constant is stored to the same location twice.

Reviewed-by: Song Gao <gaosong@loongson.cn>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
ab84dc398b tcg/optimize: Optimize env memory operations
Propagate stores to loads, loads to loads.

Reviewed-by: Song Gao <gaosong@loongson.cn>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
9f75e52828 tcg/optimize: Split out cmp_better_copy
Compare two temps for "better", split out from finding
the best from a whole list.  Use TCGKind, which already
gives the proper priority.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
986cac1d2a tcg/optimize: Pipe OptContext into reset_ts
Will be needed in the next patch.

Reviewed-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
9628d008bd tcg: Don't free vector results
Avoid reusing vector temporaries so that we may re-use them
when propagating stores to loads.

Reviewed-by: Song Gao <gaosong@loongson.cn>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
b701f195d3 tcg: Remove TCG_TARGET_HAS_neg_{i32,i64}
The movcond opcode is now mandatory for backends to implement.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231026041404.1229328-7-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
0fbee2b764 tcg/loongarch64: Implement neg opcodes
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231026041404.1229328-6-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
e0448a8b71 tcg/mips: Implement neg opcodes
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231026041404.1229328-5-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
3871be753f tcg: Remove TCG_TARGET_HAS_movcond_{i32,i64}
The movcond opcode is now mandatory for backends to implement.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231026041404.1229328-4-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
2cff741da8 tcg/mips: Always implement movcond
Expand as branch over move if not supported in the ISA.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231026041404.1229328-3-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
42221a64da tcg/mips: Split out tcg_out_setcond_int
Return the temp and a set of flags, to be used as a
primitive for setcond, brcond, movcond.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231026041404.1229328-2-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
58b797130c tcg: Move tcg_temp_free_* out of line
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231029210848.78234-12-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
4643f3e07e tcg: Move tcg_temp_new_*, tcg_global_mem_new_* out of line
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231029210848.78234-11-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
16edaee720 tcg: Move tcg_constant_* out of line
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231029210848.78234-10-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
17b9fadb1d tcg: Unexport tcg_gen_op*_{i32,i64}
These functions are no longer used outside tcg-op.c.
There are several that are completely unused, so remove them.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231029210848.78234-9-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
1d67bf545f tcg: Move tcg_gen_opN declarations to tcg-internal.h
These are used within tcg-op.c and tcg-op-ldst.c.
There are no uses outside tcg/.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231029210848.78234-8-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
27c758fd22 tcg: Move vec_gen_* declarations to tcg-internal.h
These are used within tcg-op-vec.c and tcg/host/tcg-target.c.inc.
There are no uses outside tcg/.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231029210848.78234-7-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
e0de2f5580 tcg: Move 64-bit expanders out of line
This one is more complicated, combining 32-bit and 64-bit
expansion with C if instead of preprocessor #if.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231029210848.78234-6-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
09607d35f5 tcg: Move 32-bit expanders out of line
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231029210848.78234-5-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
01bbb6e3eb tcg: Move generic expanders out of line
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231029210848.78234-4-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
6fc75d50a5 tcg: Move tcg_gen_op* out of line
In addition to moving out of line, with CONFIG_DEBUG_TCG
mark them all noinline.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231029210848.78234-3-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
ecfa1877f7 tcg: Mark tcg_gen_op* as noinline
Encourage the compiler to tail-call rather than inline
across the dozens of opcode expanders.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231029210848.78234-2-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
6046f6e94d accel/tcg: Fix condition for store_atom_insert_al16
Store bytes under a mask is fundamentally a cmpxchg, not a straight store.
Use HAVE_CMPXCHG128 instead of HAVE_ATOMIC128_RW.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230916220151.526140-8-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
8b1b3db71a accel/tcg: Remove redundant case in store_atom_16
We handled the HAVE_ATOMIC128_RW case with atomic16_set at the top of
the function; the only thing left for a host without that support is
to fall through to cpu_loop_exit_atomic.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230916220151.526140-7-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
adc8467e69 host/include/loongarch64: Add atomic16 load and store
While loongarch64 does not have a 128-bit cmpxchg, it does
have 128-bit atomic load and store via the vector unit.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230916220151.526140-6-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
f2a553481e tcg/loongarch64: Use cpuinfo.h
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Jiajie Chen <c@jia.je>
Message-Id: <20230916220151.526140-5-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
0885f1221e util: Add cpuinfo for loongarch64
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Jiajie Chen <c@jia.je>
Message-Id: <20230916220151.526140-4-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
2b2ae0a42e tcg/loongarch64: Use C_N2_I1 for INDEX_op_qemu_ld_a*_i128
Use new registers for the output, so that we never overlap
the input address, which could happen for user-only.
This avoids a "tmp = addr + 0" in that case.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Jiajie Chen <c@jia.je>
Message-Id: <20230916220151.526140-3-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
fa645b48d3 tcg: Add C_N2_I1
Constraint with two outputs, both in new registers.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Jiajie Chen <c@jia.je>
Message-Id: <20230916220151.526140-2-richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Richard Henderson
24a4d59aa7 accel/tcg: Move HMP info jit and info opcount code
Move all of it into accel/tcg/monitor.c.  This puts everything
about tcg that is only used by the monitor in the same place.

Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-11-06 08:27:21 -08:00
Naohiro Aota
ad4feaca61 file-posix: fix over-writing of returning zone_append offset
raw_co_zone_append() sets "s->offset" where "BDRVRawState *s". This pointer
is used later at raw_co_prw() to save the block address where the data is
written.

When multiple IOs are on-going at the same time, a later IO's
raw_co_zone_append() call over-writes a former IO's offset address before
raw_co_prw() completes. As a result, the former zone append IO returns the
initial value (= the start address of the writing zone), instead of the
proper address.

Fix the issue by passing the offset pointer to raw_co_prw() instead of
passing it through s->offset. Also, remove "offset" from BDRVRawState as
there is no usage anymore.

Fixes: 4751d09adc ("block: introduce zone append write for zoned devices")
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Message-Id: <20231030073853.2601162-1-naohiro.aota@wdc.com>
Reviewed-by: Sam Li <faithilikerun@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
2023-11-06 16:15:07 +01:00
Sam Li
10b9e0802a block/file-posix: fix update_zones_wp() caller
When the zoned request fail, it needs to update only the wp of
the target zones for not disrupting the in-flight writes on
these other zones. The wp is updated successfully after the
request completes.

Fixed the callers with right offset and nr_zones.

Signed-off-by: Sam Li <faithilikerun@gmail.com>
Message-Id: <20230825040556.4217-1-faithilikerun@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
[hreitz: Rebased and fixed comment spelling]
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
2023-11-06 16:15:07 +01:00
Jean-Louis Dupond
b2b109041e qcow2: keep reference on zeroize with discard-no-unref enabled
When the discard-no-unref flag is enabled, we keep the reference for
normal discard requests.
But when a discard is executed on a snapshot/qcow2 image with backing,
the discards are saved as zero clusters in the snapshot image.

When committing the snapshot to the backing file, not
discard_in_l2_slice is called but zero_in_l2_slice. Which did not had
any logic to keep the reference when discard-no-unref is enabled.

Therefor we add logic in the zero_in_l2_slice call to keep the reference
on commit.

Fixes: https://gitlab.com/qemu-project/qemu/-/issues/1621
Signed-off-by: Jean-Louis Dupond <jean-louis@dupond.be>
Message-Id: <20231003125236.216473-2-jean-louis@dupond.be>
[hreitz: Made the documentation change more verbose, as discussed
         on-list]
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
2023-11-06 16:15:07 +01:00
Peter Maydell
5722fc4712 target/arm: Fix A64 LDRA immediate decode
In commit be23a049 in the conversion to decodetree we broke the
decoding of the immediate value in the LDRA instruction.  This should
be a 10 bit signed value that is scaled by 8, but in the conversion
we incorrectly ended up scaling it only by 2.  Fix the scaling
factor.

Cc: qemu-stable@nongnu.org
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1970
Fixes: be23a049 ("target/arm: Convert load (pointer auth) insns to decodetree")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20231106113445.1163063-1-peter.maydell@linaro.org
2023-11-06 15:00:29 +00:00
Peter Maydell
13edcf591e hw/arm/vexpress-a9: Remove useless mapping of RAM at address 0
On the vexpress-a9 board we try to map both RAM and flash to address 0,
as seen in "info mtree":

address-space: memory
  0000000000000000-ffffffffffffffff (prio 0, i/o): system
    0000000000000000-0000000003ffffff (prio 0, romd): alias vexpress.flashalias @vexpress.flash0 0000000000000000-0000000003ffffff
    0000000000000000-0000000003ffffff (prio 0, ram): alias vexpress.lowmem @vexpress.highmem 0000000000000000-0000000003ffffff
    0000000010000000-0000000010000fff (prio 0, i/o): arm-sysctl
    0000000010004000-0000000010004fff (prio 0, i/o): pl041
(etc)

The flash "wins" and the RAM mapping is useless (but also harmless).

This happened as a result of commit 6ec1588e in 2014, which changed
"we always map the RAM to the low addresses for vexpress-a9" to "we
always map flash in the low addresses", but forgot to stop mapping
the RAM.

In real hardware, this low part of memory is remappable, both at
runtime by the guest writing to a control register, and configurably
as to what you get out of reset -- you can have the first flash
device, or the second, or the DDR2 RAM, or the external AXI bus
(which for QEMU means "nothing there").  In an ideal world we would
support that remapping both at runtime and via a machine property to
select the out-of-reset behaviour.

Pending anybody caring enough to implement the full remapping
behaviour:
 * remove the useless mapped-but-inaccessible lowram MR
 * document that QEMU doesn't support remapping of low memory

Fixes: 6ec1588e ("hw/arm/vexpress: Alias NOR flash at 0 for vexpress-a9")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1761
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20231103185602.875849-1-peter.maydell@linaro.org
2023-11-06 15:00:29 +00:00