[PATCH v4 kvmtool 00/12] arm64: Allow the user to set RAM base address
Alexandru Elisei
alexandru.elisei at arm.com
Thu Jun 16 06:48:16 PDT 2022
The series can be found at [1]. It is loosely based on the patches that
allow the user to define the VM memory layout (RAM + MMIO) [2]. I've
cherry-picked a handful of patches from that series, the rest I wrote from
scratch since there have been several changes to the way guest memory is
handled. I've chosen to focus on specifying the RAM layout with only one
RAM bank and leave the rest for a later series because this was relatively
easy to accomplish, while still being very useful.
What this series does: for arm64, the user can now specify the base address
for RAM:
$ ./lkvm run -m1G at 2G .. # Equivalent to ./lkvm run -m1024
The memory units are B (bytes), K (kilobytes), M (megabytes), G
(gigabytes), T (terrabytes), P (petabytes). Lowercase is also valid.
Want to put RAM at the top of the physical address range? Easy:
$ ./lkvm run -m2G at 1022G .. # Assumes the maximum is 40 bits of IPA
There one limitation on the RAM base address: it must not overlap with the
MMIO range that kvmtool uses for arm/arm64, which lives below 2GB.
Why this is useful, in my opinion:
1. Testing how a payload handles different memory layouts without the need
to hack kvmtool or find the hardware that implements the desired layout.
2. It can serve as a development tool for adding support for larger PA
ranges for Linux and KVM (currently capped at 48 bits for 4k/16k pages), or
other payloads.
Summary of the series
======================
* The series starts with refactoring how kvm->cfg.ram_size is validated
and used, followed by several cleanups in the arm and arm64 code.
* Then patch #8 ("builtin_run: Allow standard size specifiers for memory")
introduced the ability to specify the measurement unit for memory. I
believe that typing the equivalent of 2TB in megabytes isn't appealing
for anyone.
* More cleanups in the arm/arm64 code follow, which are needed for patch
#12 ("arm64: Allow the user to specify the RAM base address"). This is
where the ability to specify the RAM base address is introduced.
Testing
=======
Same testing as before:
- Build tested each patch for all architectures.
- Ran an x86 kernel with and without setting the amount of RAM using the
memory specifiers; tested that setting the RAM address results in an
error.
- Ran an arm64 kernel without setting the size, with setting the size and
with setting the size and address; tried different addresses (2G, 3G,
256G); also tested that going below 2G or above the maximum IPA correctly
results in an error.
- Ran all arm64 kvm-unit-test tests with similar combinations of memory
size and address (instead of 256G I used 128G, as that's where I/O lives
for qemu and kvm-unit-tests maps that unconditionally as I/O).
- Ran all 32bit arm tests on an arm64 host with various combinations of
memory size and address (base address at 2G and 2.5G only due to a
limitation in the way the tests are set up).
Changelog
=========
Since v3:
* Gathered Reviewed-by tags, thank you!
* Rebased on top of current HEAD, f44af23e3a62 ("virtio/pci:
Factor MSI route creation").
* Dropped what was patch #2 ("sizes.h: Make all sizes 64bit") and opted
instead to cast SZ_64M to u64 in get_ram_size() in what is now patch #2
("builtin-run: Always use RAM size in bytes") (Andre).
* Reworked the way the unit of measurement for memory is parsed (Andre).
* Reworked the way the memory size is validated to specifically check for an
invalid number (Andre).
Since v2:
* Patch #2 ("sizes.h: Make all sizes 64bit") is new (reported by Andre).
* Casted nr_pages to u64 in host_ram_size() to avoid overflows when multiplied
by page_size on 32-bit systems with more than 2GB of RAM (Andre).
* Initialize ram_addr before parsing the command line options because the
default was at address 0, which is invalid for arm64 (Andre).
* Fix check for RAM top above 4GB for aarch32 guests.
Since v1:
* Rebased on top of current HEAD (commit 4639b72f61a3 ("arm64: Add
--vcpu-affinity command line argument")).
* Removed the last 3 patches that touched the --firmware-address command line
argument. They weren't necessary for this series, I'll resend them after this
series gets merged.
* Moved patch #8 ("builtin_run: Allow standard size specifiers for memory")
later in the series (was #6).
[1] https://gitlab.arm.com/linux-arm/kvmtool-ae/-/tree/arm-allow-the-user-to-define-ram-address-v4
[2] https://lkml.kernel.org/kvm/1569245722-23375-1-git-send-email-alexandru.elisei@arm.com/
Alexandru Elisei (9):
Use MB for megabytes consistently
builtin-run: Always use RAM size in bytes
builtin-run: Rework RAM size validation
builtin-run: Add arch hook to validate VM configuration
arm/arm64: Fail if RAM size is too large for 32-bit guests
arm/arm64: Kill the ARM_MAX_MEMORY() macro
arm/arm64: Kill the ARM_HIMAP_MAX_MEMORY() macro
Introduce kvm__arch_default_ram_address()
arm64: Allow the user to specify the RAM base address
Julien Grall (2):
kvm__arch_init: Remove hugetlbfs_path and ram_size as parameters
arm/arm64: Consolidate RAM initialization in kvm__init_ram()
Suzuki K Poulose (1):
builtin_run: Allow standard size specifiers for memory
Documentation/kvmtool.1 | 4 +-
Makefile | 1 +
arm/aarch32/include/kvm/kvm-arch.h | 2 -
arm/aarch32/kvm.c | 14 ++++
arm/aarch64/include/kvm/kvm-arch.h | 18 +----
arm/aarch64/kvm.c | 22 +++++-
arm/include/arm-common/kvm-arch.h | 1 -
arm/kvm.c | 60 ++++++++-------
builtin-run.c | 116 +++++++++++++++++++++++++----
include/kvm/kvm-config.h | 8 +-
include/kvm/kvm.h | 18 ++++-
include/linux/sizes.h | 2 +
kvm.c | 2 +-
mips/kvm.c | 16 +++-
powerpc/kvm.c | 14 +++-
riscv/kvm.c | 16 +++-
x86/kvm.c | 13 +++-
17 files changed, 247 insertions(+), 80 deletions(-)
create mode 100644 arm/aarch32/kvm.c
--
2.36.1
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