Re: [Qemu-devel] [PATCH V4 3/3] tests: Add migration test for aarch64

[Andrew Jones]

On Fri, Feb 23, 2018 at 04:13:08PM -0600, Wei Huang wrote:
> 
> 
> On 02/22/2018 03:00 AM, Andrew Jones wrote:
> > On Wed, Feb 21, 2018 at 10:44:17PM -0600, Wei Huang 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/. So users can change the
> >> source and/or re-compile the binary as they wish.
> >>
> >> Signed-off-by: Wei Huang <address@hidden>
> >> ---
> >>  tests/Makefile.include               |  1 +
> >>  tests/migration-test.c               | 47 +++++++++++++++++++++---
> >>  tests/migration/Makefile             | 12 +++++-
> >>  tests/migration/aarch64-a-b-kernel.S | 71 
> >> ++++++++++++++++++++++++++++++++++++
> >>  tests/migration/aarch64-a-b-kernel.h | 19 ++++++++++
> >>  tests/migration/migration-test.h     |  5 +++
> >>  6 files changed, 147 insertions(+), 8 deletions(-)
> >>  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 a1bcbffe12..df9f64438f 100644
> >> --- a/tests/Makefile.include
> >> +++ b/tests/Makefile.include
> >> @@ -372,6 +372,7 @@ check-qtest-arm-y += tests/sdhci-test$(EXESUF)
> >>  check-qtest-aarch64-y = tests/numa-test$(EXESUF)
> >>  check-qtest-aarch64-y += 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 e2e06ed337..a4f6732a59 100644
> >> --- a/tests/migration-test.c
> >> +++ b/tests/migration-test.c
> >> @@ -11,6 +11,7 @@
> >>   */
> >>  
> >>  #include "qemu/osdep.h"
> >> +#include <sys/utsname.h>
> >>  
> >>  #include "libqtest.h"
> >>  #include "qapi/qmp/qdict.h"
> >> @@ -23,8 +24,8 @@
> >>  
> >>  #include "migration/migration-test.h"
> >>  
> >> -const unsigned start_address = TEST_MEM_START;
> >> -const unsigned end_address = TEST_MEM_END;
> >> +unsigned start_address = TEST_MEM_START;
> >> +unsigned end_address = TEST_MEM_END;
> >>  bool got_stop;
> >>  
> >>  #if defined(__linux__)
> >> @@ -81,12 +82,13 @@ static const char *tmpfs;
> >>   * outputting a 'B' every so often if it's still running.
> >>   */
> >>  #include "tests/migration/x86-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);
> >>  }
> >>  
> >> @@ -393,7 +395,7 @@ static void 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"
> >> @@ -422,6 +424,39 @@ static void test_migrate_start(QTestState **from, 
> >> QTestState **to,
> >>                                    " -serial file:%s/dest_serial"
> >>                                    " -incoming %s",
> >>                                    accel, tmpfs, uri);
> >> +    } else if (strcmp(arch, "aarch64") == 0) {
> >> +        const char *cpu;
> >> +        const char *gic_ver;
> >> +        struct utsname utsname;
> >> +
> >> +        /* kvm and tcg need different cpu and gic-version configs */
> >> +        if (access("/dev/kvm", F_OK) == 0 && uname(&utsname) == 0 &&
> >> +            strcmp(utsname.machine, "aarch64") == 0) {
> >> +            accel = "kvm";
> >> +            cpu = "host";
> >> +            gic_ver = "host";
> >> +        } else {
> >> +            accel = "tcg";
> >> +            cpu = "cortex-a57";
> >> +            gic_ver = "2";
> >> +        }
> >> +
> >> +        init_bootfile(bootpath, aarch64_kernel);
> >> +        cmd_src = g_strdup_printf("-machine virt,accel=%s,gic-version=%s "
> >> +                                  "-name vmsource,debug-threads=on -cpu 
> >> %s "
> >> +                                  "-m 150M -serial file:%s/src_serial "
> >> +                                  "-kernel %s ",
> >> +                                  accel, gic_ver, cpu, tmpfs, bootpath);
> >> +        cmd_dst = g_strdup_printf("-machine virt,accel=%s,gic-version=%s "
> >> +                                  "-name vmdest,debug-threads=on -cpu %s "
> >> +                                  "-m 150M -serial file:%s/dest_serial "
> >> +                                  "-kernel %s "
> >> +                                  "-incoming %s ",
> >> +                                  accel, gic_ver, cpu, tmpfs, bootpath, 
> >> uri);
> >> +
> >> +        /* aarch64 virt machine physical memory starts at 0x40000000 */
> >> +        start_address = ARM_TEST_MEM_START;
> >> +        end_address = ARM_TEST_MEM_END;
> >>      } else {
> >>          g_assert_not_reached();
> >>      }
> >> @@ -506,7 +541,7 @@ 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 b768d0729d..b72d41367f 100644
> >> --- a/tests/migration/Makefile
> >> +++ b/tests/migration/Makefile
> >> @@ -15,6 +15,7 @@ cross-gcc = $(firstword $(wildcard $(patsubst 
> >> %ld,%gcc,$(call cross-ld,$(1)))))
> >>  find-cross-prefix = $(subst gcc,,$(notdir $(call cross-gcc,$(1))))
> >>  
> >>  x86_64_cross_prefix := $(call find-cross-prefix,x86_64)
> >> +aarch64_cross_prefix := $(call find-cross-prefix,aarch64)
> >>  
> >>  export __note
> >>  override define __note
> >> @@ -25,7 +26,7 @@ override define __note
> >>   */
> >>  endef
> >>  
> >> -all: x86-a-b-bootblock.h
> >> +all: x86-a-b-bootblock.h aarch64-a-b-kernel.h
> >>  
> >>  x86-a-b-bootblock.h: x86-a-b-bootblock.S
> >>    $(x86_64_cross_prefix)gcc -m32 -march=i486 -c $< -o x86.o
> >> @@ -34,5 +35,12 @@ x86-a-b-bootblock.h: x86-a-b-bootblock.S
> >>    echo "$$__note" > $@
> >>    xxd -i x86.bootsect | sed -e 's/.*int.*//' >> $@
> >>  
> >> +aarch64-a-b-kernel.h: aarch64-a-b-kernel.S
> >> +  $(aarch64_cross_prefix)gcc -o aarch64.elf -nostdlib \
> >> +          -Wl,--build-id=none,-Ttext=40080000 $<
> > 
> > Adding the arm64 Linux kernel offset here is a bit subtle. And, since the
> > TEST_MEM_START is at 1M, that only leaves 512K for test code and data.
> > I think you may want to define this offset somewhere, making it less
> > subtle, and then also factor it in when computing the test mem start.
> 
> I have fixed most parts based on your review comments, except for this
> one. I think the section address, -Ttext=, doesn't matter in this case.
> Such info is not present aarch64.kernel; plus QEMU loads the kernel into

In this case it doesn't matter because your code only uses pc-relative
addresses. It's pretty safe to assume the compiler will only emit pc-
relative addresses for code like this, so that's probably fine.

> the loader_start address, which is the physical memory base (0x40000000,
> see virt.c). So the space to store kernel binary is 1MB, which should be
> large enough to prevent aarch64-a-b-kernel.S from changing code.

No, it loads the kernel at 0x40000000 + 0x80000, see
hw/arm/boot.c:load_aarch64_image() and KERNEL64_LOAD_ADDR.

> 
> Anyway I think we are fine to remove "-Ttext=40080000" here.

Fine by me, but you might want to add a comment saying the code *must*
only compile to using pc-relative addresses.

Thanks,
drew