Re: [Qemu-devel] [PATCH V9 4/4] tests: Add migration test for aarch64

[Dr. David Alan Gilbert]

* Wei Huang (address@hidden) wrote:
> 
> 
> On 09/28/2018 09:04 AM, Dr. David Alan Gilbert wrote:
> > * Wei Huang (address@hidden) wrote:
> >>
> >>
> >> On 09/26/2018 11:31 AM, Dr. David Alan Gilbert wrote:
> >>> * Wei Huang (address@hidden) wrote:
> >>>> This patch adds migration test support for aarch64. The test code, which
> >>>> implements the same functionality as x86, is booted as a kernel in qemu.
> >>>> Here are the design choices we make for aarch64:
> >>>>
> >>>>  * We choose this -kernel approach because aarch64 QEMU doesn't provide a
> >>>>    built-in fw like x86 does. So instead of relying on a boot loader, we
> >>>>    use -kernel approach for aarch64.
> >>>>  * The serial output is sent to PL011 directly.
> >>>>  * The physical memory base for mach-virt machine is 0x40000000. We 
> >>>> change
> >>>>    the start_address and end_address for aarch64.
> >>>>
> >>>> In addition to providing the binary, this patch also includes the source
> >>>> code and the build script in tests/migration/aarch64. So users can change
> >>>> the source and/or re-compile the binary as they wish.
> >>>>
> >>>> Reviewed-by: Juan Quintela <address@hidden>
> >>>> Signed-off-by: Wei Huang <address@hidden>
> >>>
> >>> I've had to bounce this patch (kept the other 3) because the test
> >>> is actually failing on aarch64 kvm.
> >>> It's about 1 in 5 for me on one of the larger (40ish core) boxes which
> >>> is otherwise idle.
> >>>
> >>> /aarch64/migration/precopy/unix: Memory content inconsistency at 43cf1000 
> >>> first_byte = 5 last_byte = 4 current = 5 hit_edge = 1
> >>> Memory content inconsistency at 43cf2000 first_byte = 5 last_byte = 4 
> >>> current = 5 hit_edge = 1
> >>> Memory content inconsistency at 43cf3000 first_byte = 5 last_byte = 4 
> >>> current = 5 hit_edge = 1
> >>> Memory content inconsistency at 43cf4000 first_byte = 5 last_byte = 4 
> >>> current = 5 hit_edge = 1
> >>> Memory content inconsistency at 43cf5000 first_byte = 5 last_byte = 4 
> >>> current = 5 hit_edge = 1
> >>> Memory content inconsistency at 43cf6000 first_byte = 5 last_byte = 4 
> >>> current = 5 hit_edge = 1
> >>> Memory content inconsistency at 43cf7000 first_byte = 5 last_byte = 4 
> >>> current = 5 hit_edge = 1
> >>
> >> Thanks, Dave. The root cause is the wrong place of cache invalidation.
> >> Here is the fix which has been tested on Amberwing. Could you please
> >> verify it from your side? After that, I can either send in a new patch
> >> or you can help me revise the existing one.
> > 
> > Thanks, I'll grab a box and try it.
> > If it works I'd prefer if you can resubmit the patch with the fix in.
> > 
> > However, this fix looks suspicious to me.  We check the guest ram
> > contents after we stop the guest;  if the guests RAM is inconsistent as
> > seen by QEMU without the 'dc' then how will this work with normal
> > applications?
> 
> Such cases happened before. Here is the one presentation given at KVM
> Forum:
> https://events.static.linuxfound.org/sites/events/files/slides/slides_10.pdf.

I have seen that presentation but I don't understand how it relates to
your case.   Imagine that we're migrating some totally arbitrary
application - how do we know we get consistent memory  - if you're
having to put cache clears in the application that sounds like it's a
real kvm/arm bug that needs fixing.

Dave

> > 
> > Shouldn't this be something qemu or kvm is doing when it stops the
> > guest?
> > 
> > Dave
> > 
> >> Thanks,
> >> -Wei
> >>
> >>
> >> diff --git a/tests/migration/aarch64/a-b-kernel.S
> >> b/tests/migration/aarch64/a-b-
> >> index 507af30..c8d2720 100644
> >> --- a/tests/migration/aarch64/a-b-kernel.S
> >> +++ b/tests/migration/aarch64/a-b-kernel.S
> >> @@ -50,15 +50,15 @@ mainloop:
> >>          mov     x4, x0
> >>
> >>  innerloop:
> >> -        /* clean cache because el2 might still cache guest data under
> >> KVM */
> >> -        dc      civac, x4
> >> -
> >>          /* increment the first byte of each page by 1 */
> >>          ldrb    w3, [x4]
> >>          add     w3, w3, #1
> >>          and     w3, w3, #0xff
> >>          strb    w3, [x4]
> >>
> >> +        /* clean cache because el2 might still cache guest data under
> >> KVM */
> >> +        dc      civac, x4
> >> +
> >>          add     x4, x4, #TEST_MEM_PAGE_SIZE
> >>          cmp     x4, x1
> >>          blt     innerloop
> >>
> >>
> >>>
> >>> Dave
> >>>
> >>>> ---
> >>>>  tests/Makefile.include               |  1 +
> >>>>  tests/migration-test.c               | 27 +++++++++++--
> >>>>  tests/migration/Makefile             |  2 +-
> >>>>  tests/migration/aarch64/Makefile     | 20 ++++++++++
> >>>>  tests/migration/aarch64/a-b-kernel.S | 75 
> >>>> ++++++++++++++++++++++++++++++++++++
> >>>>  tests/migration/aarch64/a-b-kernel.h | 19 +++++++++
> >>>>  tests/migration/migration-test.h     |  9 +++++
> >>>>  7 files changed, 148 insertions(+), 5 deletions(-)
> >>>>  create mode 100644 tests/migration/aarch64/Makefile
> >>>>  create mode 100644 tests/migration/aarch64/a-b-kernel.S
> >>>>  create mode 100644 tests/migration/aarch64/a-b-kernel.h
> >>>>
> >>>> diff --git a/tests/Makefile.include b/tests/Makefile.include
> >>>> index 87c81d1..fab8fb9 100644
> >>>> --- a/tests/Makefile.include
> >>>> +++ b/tests/Makefile.include
> >>>> @@ -390,6 +390,7 @@ check-qtest-arm-y += tests/hexloader-test$(EXESUF)
> >>>>  check-qtest-aarch64-y = tests/numa-test$(EXESUF)
> >>>>  check-qtest-aarch64-$(CONFIG_SDHCI) += tests/sdhci-test$(EXESUF)
> >>>>  check-qtest-aarch64-y += tests/boot-serial-test$(EXESUF)
> >>>> +check-qtest-aarch64-y += tests/migration-test$(EXESUF)
> >>>>  
> >>>>  check-qtest-microblazeel-y = $(check-qtest-microblaze-y)
> >>>>  
> >>>> diff --git a/tests/migration-test.c b/tests/migration-test.c
> >>>> index 17c6896..ecfae0b 100644
> >>>> --- a/tests/migration-test.c
> >>>> +++ b/tests/migration-test.c
> >>>> @@ -86,12 +86,13 @@ static const char *tmpfs;
> >>>>   * repeatedly. It outputs a 'B' at a fixed rate while it's still 
> >>>> running.
> >>>>   */
> >>>>  #include "tests/migration/i386/a-b-bootblock.h"
> >>>> +#include "tests/migration/aarch64/a-b-kernel.h"
> >>>>  
> >>>> -static void init_bootfile_x86(const char *bootpath)
> >>>> +static void init_bootfile(const char *bootpath, void *content)
> >>>>  {
> >>>>      FILE *bootfile = fopen(bootpath, "wb");
> >>>>  
> >>>> -    g_assert_cmpint(fwrite(x86_bootsect, 512, 1, bootfile), ==, 1);
> >>>> +    g_assert_cmpint(fwrite(content, 512, 1, bootfile), ==, 1);
> >>>>      fclose(bootfile);
> >>>>  }
> >>>>  
> >>>> @@ -428,7 +429,7 @@ static int test_migrate_start(QTestState **from, 
> >>>> QTestState **to,
> >>>>      got_stop = false;
> >>>>  
> >>>>      if (strcmp(arch, "i386") == 0 || strcmp(arch, "x86_64") == 0) {
> >>>> -        init_bootfile_x86(bootpath);
> >>>> +        init_bootfile(bootpath, x86_bootsect);
> >>>>          cmd_src = g_strdup_printf("-machine accel=%s -m 150M"
> >>>>                                    " -name source,debug-threads=on"
> >>>>                                    " -serial file:%s/src_serial"
> >>>> @@ -459,6 +460,24 @@ static int test_migrate_start(QTestState **from, 
> >>>> QTestState **to,
> >>>>  
> >>>>          start_address = PPC_TEST_MEM_START;
> >>>>          end_address = PPC_TEST_MEM_END;
> >>>> +    } else if (strcmp(arch, "aarch64") == 0) {
> >>>> +        init_bootfile(bootpath, aarch64_kernel);
> >>>> +        cmd_src = g_strdup_printf("-machine 
> >>>> virt,accel=%s,gic-version=max "
> >>>> +                                  "-name vmsource,debug-threads=on -cpu 
> >>>> max "
> >>>> +                                  "-m 150M -serial file:%s/src_serial "
> >>>> +                                  "-kernel %s ",
> >>>> +                                  accel, tmpfs, bootpath);
> >>>> +        cmd_dst = g_strdup_printf("-machine 
> >>>> virt,accel=%s,gic-version=max "
> >>>> +                                  "-name vmdest,debug-threads=on -cpu 
> >>>> max "
> >>>> +                                  "-m 150M -serial file:%s/dest_serial "
> >>>> +                                  "-kernel %s "
> >>>> +                                  "-incoming %s ",
> >>>> +                                  accel, tmpfs, bootpath, uri);
> >>>> +
> >>>> +        start_address = ARM_TEST_MEM_START;
> >>>> +        end_address = ARM_TEST_MEM_END;
> >>>> +
> >>>> +        g_assert(sizeof(aarch64_kernel) <= ARM_TEST_MAX_KERNEL_SIZE);
> >>>>      } else {
> >>>>          g_assert_not_reached();
> >>>>      }
> >>>> @@ -545,7 +564,7 @@ static void test_deprecated(void)
> >>>>  {
> >>>>      QTestState *from;
> >>>>  
> >>>> -    from = qtest_start("");
> >>>> +    from = qtest_start("-machine none");
> >>>>  
> >>>>      deprecated_set_downtime(from, 0.12345);
> >>>>      deprecated_set_speed(from, 12345);
> >>>> diff --git a/tests/migration/Makefile b/tests/migration/Makefile
> >>>> index a9ed875..13af934 100644
> >>>> --- a/tests/migration/Makefile
> >>>> +++ b/tests/migration/Makefile
> >>>> @@ -5,7 +5,7 @@
> >>>>  # See the COPYING file in the top-level directory.
> >>>>  #
> >>>>  
> >>>> -TARGET_LIST = i386
> >>>> +TARGET_LIST = i386 aarch64
> >>>>  
> >>>>  SRC_PATH = ../..
> >>>>  
> >>>> diff --git a/tests/migration/aarch64/Makefile 
> >>>> b/tests/migration/aarch64/Makefile
> >>>> new file mode 100644
> >>>> index 0000000..d440fa8
> >>>> --- /dev/null
> >>>> +++ b/tests/migration/aarch64/Makefile
> >>>> @@ -0,0 +1,20 @@
> >>>> +# To specify cross compiler prefix, use CROSS_PREFIX=
> >>>> +#   $ make CROSS_PREFIX=aarch64-linux-gnu-
> >>>> +
> >>>> +.PHONY: all clean
> >>>> +all: a-b-kernel.h
> >>>> +
> >>>> +a-b-kernel.h: aarch64.kernel
> >>>> +        echo "$$__note" > header.tmp
> >>>> +        xxd -i $< | sed -e 's/.*int.*//' >> header.tmp
> >>>> +        mv header.tmp $@
> >>>> +
> >>>> +aarch64.kernel: aarch64.elf
> >>>> +        $(CROSS_PREFIX)objcopy -O binary $< $@
> >>>> +
> >>>> +aarch64.elf: a-b-kernel.S
> >>>> +        $(CROSS_PREFIX)gcc -o $@ -nostdlib -Wl,--build-id=none $<
> >>>> +
> >>>> +clean:
> >>>> +        @rm -rf *.kernel *.elf
> >>>> +
> >>>> diff --git a/tests/migration/aarch64/a-b-kernel.S 
> >>>> b/tests/migration/aarch64/a-b-kernel.S
> >>>> new file mode 100644
> >>>> index 0000000..507af30
> >>>> --- /dev/null
> >>>> +++ b/tests/migration/aarch64/a-b-kernel.S
> >>>> @@ -0,0 +1,75 @@
> >>>> +#
> >>>> +# Copyright (c) 2018 Red Hat, Inc. and/or its affiliates
> >>>> +#
> >>>> +# Author:
> >>>> +#   Wei Huang <address@hidden>
> >>>> +#
> >>>> +# This work is licensed under the terms of the GNU GPL, version 2 or 
> >>>> later.
> >>>> +# See the COPYING file in the top-level directory.
> >>>> +#
> >>>> +# Note: Please make sure the compiler compiles the assembly code below 
> >>>> with
> >>>> +# pc-relative address. Also the branch instructions should use relative
> >>>> +# addresses only.
> >>>> +
> >>>> +#include "../migration-test.h"
> >>>> +
> >>>> +.section .text
> >>>> +
> >>>> +        .globl  _start
> >>>> +
> >>>> +_start:
> >>>> +        /* disable MMU to use phys mem address */
> >>>> +        mrs     x0, sctlr_el1
> >>>> +        bic     x0, x0, #(1<<0)
> >>>> +        msr     sctlr_el1, x0
> >>>> +        isb
> >>>> +
> >>>> +        /* traverse test memory region */
> >>>> +        mov     x0, #ARM_TEST_MEM_START
> >>>> +        mov     x1, #ARM_TEST_MEM_END
> >>>> +
> >>>> +        /* output char 'A' to PL011 */
> >>>> +        mov     w3, 'A'
> >>>> +        mov     x2, #ARM_MACH_VIRT_UART
> >>>> +        strb    w3, [x2]
> >>>> +
> >>>> +        /* clean up memory */
> >>>> +        mov     w3, #0
> >>>> +        mov     x4, x0
> >>>> +clean:
> >>>> +        strb    w3, [x4]
> >>>> +        add     x4, x4, #TEST_MEM_PAGE_SIZE
> >>>> +        cmp     x4, x1
> >>>> +        ble     clean
> >>>> +
> >>>> +        /* w5 keeps a counter so we can limit the output speed */
> >>>> +        mov     w5, #0
> >>>> +
> >>>> +        /* main body */
> >>>> +mainloop:
> >>>> +        mov     x4, x0
> >>>> +
> >>>> +innerloop:
> >>>> +        /* clean cache because el2 might still cache guest data under 
> >>>> KVM */
> >>>> +        dc      civac, x4
> >>>> +
> >>>> +        /* increment the first byte of each page by 1 */
> >>>> +        ldrb    w3, [x4]
> >>>> +        add     w3, w3, #1
> >>>> +        and     w3, w3, #0xff
> >>>> +        strb    w3, [x4]
> >>>> +
> >>>> +        add     x4, x4, #TEST_MEM_PAGE_SIZE
> >>>> +        cmp     x4, x1
> >>>> +        blt     innerloop
> >>>> +
> >>>> +        add     w5, w5, #1
> >>>> +        and     w5, w5, #0xff
> >>>> +        cmp     w5, #0
> >>>> +        bne     mainloop
> >>>> +
> >>>> +        /* output char 'B' to PL011 */
> >>>> +        mov     w3, 'B'
> >>>> +        strb    w3, [x2]
> >>>> +
> >>>> +        b       mainloop
> >>>> diff --git a/tests/migration/aarch64/a-b-kernel.h 
> >>>> b/tests/migration/aarch64/a-b-kernel.h
> >>>> new file mode 100644
> >>>> index 0000000..521125e
> >>>> --- /dev/null
> >>>> +++ b/tests/migration/aarch64/a-b-kernel.h
> >>>> @@ -0,0 +1,19 @@
> >>>> +/* This file is automatically generated from the assembly file in
> >>>> + * tests/migration/aarch64. Edit that file and then run "make all"
> >>>> + * inside tests/migration to update, and then remember to send both
> >>>> + * the header and the assembler differences in your patch submission.
> >>>> + */
> >>>> +unsigned char aarch64_kernel[] = {
> >>>> +  0x00, 0x10, 0x38, 0xd5, 0x00, 0xf8, 0x7f, 0x92, 0x00, 0x10, 0x18, 
> >>>> 0xd5,
> >>>> +  0xdf, 0x3f, 0x03, 0xd5, 0x00, 0x02, 0xa8, 0xd2, 0x01, 0xc8, 0xa8, 
> >>>> 0xd2,
> >>>> +  0x23, 0x08, 0x80, 0x52, 0x02, 0x20, 0xa1, 0xd2, 0x43, 0x00, 0x00, 
> >>>> 0x39,
> >>>> +  0x03, 0x00, 0x80, 0x52, 0xe4, 0x03, 0x00, 0xaa, 0x83, 0x00, 0x00, 
> >>>> 0x39,
> >>>> +  0x84, 0x04, 0x40, 0x91, 0x9f, 0x00, 0x01, 0xeb, 0xad, 0xff, 0xff, 
> >>>> 0x54,
> >>>> +  0x05, 0x00, 0x80, 0x52, 0xe4, 0x03, 0x00, 0xaa, 0x24, 0x7e, 0x0b, 
> >>>> 0xd5,
> >>>> +  0x83, 0x00, 0x40, 0x39, 0x63, 0x04, 0x00, 0x11, 0x63, 0x1c, 0x00, 
> >>>> 0x12,
> >>>> +  0x83, 0x00, 0x00, 0x39, 0x84, 0x04, 0x40, 0x91, 0x9f, 0x00, 0x01, 
> >>>> 0xeb,
> >>>> +  0x2b, 0xff, 0xff, 0x54, 0xa5, 0x04, 0x00, 0x11, 0xa5, 0x1c, 0x00, 
> >>>> 0x12,
> >>>> +  0xbf, 0x00, 0x00, 0x71, 0x81, 0xfe, 0xff, 0x54, 0x43, 0x08, 0x80, 
> >>>> 0x52,
> >>>> +  0x43, 0x00, 0x00, 0x39, 0xf1, 0xff, 0xff, 0x17
> >>>> +};
> >>>> +
> >>>> diff --git a/tests/migration/migration-test.h 
> >>>> b/tests/migration/migration-test.h
> >>>> index c4c0c52..6939a13 100644
> >>>> --- a/tests/migration/migration-test.h
> >>>> +++ b/tests/migration/migration-test.h
> >>>> @@ -18,4 +18,13 @@
> >>>>  #define PPC_TEST_MEM_START (1 * 1024 * 1024)
> >>>>  #define PPC_TEST_MEM_END   (100 * 1024 * 1024)
> >>>>  
> >>>> +/* ARM */
> >>>> +#define ARM_TEST_MEM_START (0x40000000 + 1 * 1024 * 1024)
> >>>> +#define ARM_TEST_MEM_END   (0x40000000 + 100 * 1024 * 1024)
> >>>> +#define ARM_MACH_VIRT_UART 0x09000000
> >>>> +/* AArch64 kernel load address is 0x40080000, and the test memory 
> >>>> starts at
> >>>> + * 0x40100000. So the maximum allowable kernel size is 512KB.
> >>>> + */
> >>>> +#define ARM_TEST_MAX_KERNEL_SIZE (512 * 1024)
> >>>> +
> >>>>  #endif /* _TEST_MIGRATION_H_ */
> >>>> -- 
> >>>> 1.8.3.1
> >>>>
> >>>>
> >>> --
> >>> Dr. David Alan Gilbert / address@hidden / Manchester, UK
> >>>
> > --
> > Dr. David Alan Gilbert / address@hidden / Manchester, UK
> > 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK