Hi Alexandru, On 11/5/23 18:16, Alexandru Elisei wrote:
Hi, I had a v2 almost finished a few months ago (maybe a year), but I parked the patches when we decided that the best thing to do was to have UEFI support in first, then rework the cache maintenance - that way, the changes can be tested on baremetal, which is much more unforgiving than KVM. Unfortunately I've been busy with other things and I don't know when I'll be able to come back to this. So I've pushed the work-in-progress here [1], with what I hope is a helpful changelog since v1. If my memory serves me right, even though it is marked as wip, it was running just fine under KVM and I was waiting for UEFI to test it on baremetal before posting. I don't know when I'll have the time to get back to the series, so if anyone is still interested, feel free to pick it up. If someone does pick up the series, they can drop/rework patches as they see fit, and I'll try to do my best to review whatever is posted on the list (but no promises). [1] https://gitlab.arm.com/linux-arm/kvm-unit-tests-ae/-/tree/arm-arm64-rework-cache-maintenance-at-boot-v2-wip2
I'm willing to take your work. But I can't open your link posted in [1]. I don't have permission to access it. Could you please posted it on a public place?
Thanks, Shaoqin
Thanks, Alex On Tue, Aug 09, 2022 at 10:15:39AM +0100, Alexandru Elisei wrote:I got the idea for this series as I was looking at the UEFI support series [1]. More specifically, I realized that the cache maintenance performed by asm_mmu_disable is insuficient. Patch #19 ("arm/arm64: Rework the cache maintenance in asm_mmu_disable") describes what is wrong with asm_mmu_disable. A detailed explanation of what cache maintenance is needed and why is needed can be found in patch #18 ("arm/arm64: Perform dcache maintenance at boot"). Then I realized that I couldn't fix only asm_mmu_disable, and leave the rest of kvm-unit-tests without the needed cache maintenance, so here it is, my attempt at adding the cache maintenace operations (from now on, CMOs) required by the architecture. My approach is to try to enable the MMU and build the translation tables as soon as possible, to avoid as much of cache maintenance as possible. I didn't want to do it in the early assembly code, like Linux, because I like the fact that kvm-unit-tests keeps the assembly code to a minimum, and I wanted to preserve that. So I made the physical allocator simpler (patches #2-#6) so it can be used to create the translation tables immediately after the memory regions are populated. After moving some code around, especially how the secondaries are brought online, the dcache maintenance is implemented in patch #18 ("arm/arm64: Perform dcache maintenance at boot"). The series is an RFC, and I open to suggestions about how to do things better; I'm happy to rework the entire series if a better approach is proposed. Why is this needed? Nobody complained about test failing because of missing CMOs before, so why add them now? I see two reasons for the series: 1. For architectural correctness. The emphasis has been so far on the test themselves to be architectural compliant, but I believe that the boot code should get the same treatment. kvm-unit-tests has started to be used in different ways than before, and I don't think that we should limit ourselves to running under one hypervisor, or running under a hypervisor at all. Which brings me to point number 2. 2. If nothing else, this can serve as a showcase for the UEFI support series for the required cache maintenance. Although I hope that UEFI support will end up sharing at least some of the boot code with the non-UEFI boot path. This is an RFC and has some rough edges, probably also bugs, but I believe the concept to be sound. If/when the series stabilizes, I'll probably split it into separate series (for example, the __ASSEMBLY__ define patch could probably be separate from the others). Tested by running all the arm and arm64 tests on a rockpro64 with qemu. [1] https://lore.kernel.org/all/20220630100324.3153655-1-nikos.nikoleris@xxxxxxx/ Alexandru Elisei (19): Makefile: Define __ASSEMBLY__ for assembly files lib/alloc_phys: Initialize align_min lib/alloc_phys: Use phys_alloc_aligned_safe and rename it to memalign_early powerpc: Use the page allocator lib/alloc_phys: Remove locking lib/alloc_phys: Remove allocation accounting arm/arm64: Mark the phys_end parameter as unused in setup_mmu() arm/arm64: Use pgd_alloc() to allocate mmu_idmap arm/arm64: Zero secondary CPUs' stack arm/arm64: Enable the MMU early arm/arm64: Map the UART when creating the translation tables arm/arm64: assembler.h: Replace size with end address for dcache_by_line_op arm: page.h: Add missing libcflat.h include arm/arm64: Add C functions for doing cache maintenance lib/alloc_phys: Add callback to perform cache maintenance arm/arm64: Allocate secondaries' stack using the page allocator arm/arm64: Configure secondaries' stack before enabling the MMU arm/arm64: Perform dcache maintenance at boot arm/arm64: Rework the cache maintenance in asm_mmu_disable Makefile | 5 +- arm/Makefile.arm | 4 +- arm/Makefile.arm64 | 4 +- arm/Makefile.common | 4 +- arm/cstart.S | 59 ++++++++++++------ arm/cstart64.S | 56 +++++++++++++---- lib/alloc_phys.c | 122 ++++++++++++------------------------- lib/alloc_phys.h | 13 +++- lib/arm/asm/assembler.h | 15 ++--- lib/arm/asm/cacheflush.h | 1 + lib/arm/asm/mmu-api.h | 1 + lib/arm/asm/mmu.h | 6 -- lib/arm/asm/page.h | 2 + lib/arm/asm/pgtable.h | 52 ++++++++++++++-- lib/arm/asm/thread_info.h | 3 +- lib/arm/cache.S | 89 +++++++++++++++++++++++++++ lib/arm/io.c | 5 ++ lib/arm/io.h | 3 + lib/arm/mmu.c | 60 +++++++++++------- lib/arm/processor.c | 6 +- lib/arm/setup.c | 66 ++++++++++++++++---- lib/arm/smp.c | 9 ++- lib/arm64/asm/assembler.h | 11 ++-- lib/arm64/asm/cacheflush.h | 32 ++++++++++ lib/arm64/asm/mmu.h | 5 -- lib/arm64/asm/pgtable.h | 67 ++++++++++++++++++-- lib/arm64/cache.S | 85 ++++++++++++++++++++++++++ lib/arm64/processor.c | 5 +- lib/devicetree.c | 2 +- lib/powerpc/setup.c | 8 +++ powerpc/Makefile.common | 1 + powerpc/cstart64.S | 1 - powerpc/spapr_hcall.c | 5 +- 33 files changed, 608 insertions(+), 199 deletions(-) create mode 100644 lib/arm/asm/cacheflush.h create mode 100644 lib/arm/cache.S create mode 100644 lib/arm64/asm/cacheflush.h create mode 100644 lib/arm64/cache.S -- 2.37.1
-- Shaoqin
