Re: [PATCH 4/4] tools/tests: Memory Claims

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 17/12/2025 5:01 pm, Roger Pau Monné wrote:
> On Tue, Dec 16, 2025 at 04:32:30PM +0000, Andrew Cooper wrote:
>> Add some basic testing of the memory claims mechainsm.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

Thanks.

> Some nits below.
>
>> ---
>> CC: Anthony PERARD <anthony.perard@vates.tech>
>> CC: Michal Orzel <michal.orzel@amd.com>
>> CC: Jan Beulich <jbeulich@suse.com>
>> CC: Julien Grall <julien@xen.org>
>> CC: Roger Pau Monné <roger.pau@citrix.com>
>> CC: Stefano Stabellini <sstabellini@kernel.org>
>> ---
>>  tools/tests/Makefile                   |   1 +
>>  tools/tests/mem-claim/.gitignore       |   1 +
>>  tools/tests/mem-claim/Makefile         |  38 +++++
>>  tools/tests/mem-claim/test-mem-claim.c | 190 +++++++++++++++++++++++++
>>  4 files changed, 230 insertions(+)
>>  create mode 100644 tools/tests/mem-claim/.gitignore
>>  create mode 100644 tools/tests/mem-claim/Makefile
>>  create mode 100644 tools/tests/mem-claim/test-mem-claim.c
>>
>> diff --git a/tools/tests/Makefile b/tools/tests/Makefile
>> index e566bd169952..6477a4386dda 100644
>> --- a/tools/tests/Makefile
>> +++ b/tools/tests/Makefile
>> @@ -3,6 +3,7 @@ include $(XEN_ROOT)/tools/Rules.mk
>>  
>>  SUBDIRS-y :=
>>  SUBDIRS-y += domid
>> +SUBDIRS-y += mem-claim
>>  SUBDIRS-y += paging-mempool
>>  SUBDIRS-y += pdx
>>  SUBDIRS-y += rangeset
>> diff --git a/tools/tests/mem-claim/.gitignore b/tools/tests/mem-claim/.gitignore
>> new file mode 100644
>> index 000000000000..cfcee00b819b
>> --- /dev/null
>> +++ b/tools/tests/mem-claim/.gitignore
>> @@ -0,0 +1 @@
>> +test-mem-claim
>> diff --git a/tools/tests/mem-claim/Makefile b/tools/tests/mem-claim/Makefile
>> new file mode 100644
>> index 000000000000..76ba3e3c8bef
>> --- /dev/null
>> +++ b/tools/tests/mem-claim/Makefile
>> @@ -0,0 +1,38 @@
>> +XEN_ROOT = $(CURDIR)/../../..
>> +include $(XEN_ROOT)/tools/Rules.mk
>> +
>> +TARGET := test-mem-claim
>> +
>> +.PHONY: all
>> +all: $(TARGET)
>> +
>> +.PHONY: clean
>> +clean:
>> +	$(RM) -- *.o $(TARGET) $(DEPS_RM)
>> +
>> +.PHONY: distclean
>> +distclean: clean
>> +	$(RM) -- *~
>> +
>> +.PHONY: install
>> +install: all
>> +	$(INSTALL_DIR) $(DESTDIR)$(LIBEXEC)/tests
>> +	$(INSTALL_PROG) $(TARGET) $(DESTDIR)$(LIBEXEC)/tests
>> +
>> +.PHONY: uninstall
>> +uninstall:
>> +	$(RM) -- $(DESTDIR)$(LIBEXEC)/tests/$(TARGET)
>> +
>> +CFLAGS += $(CFLAGS_xeninclude)
>> +CFLAGS += $(CFLAGS_libxenctrl)
>> +CFLAGS += $(APPEND_CFLAGS)
>> +
>> +LDFLAGS += $(LDLIBS_libxenctrl)
>> +LDFLAGS += $(APPEND_LDFLAGS)
>> +
>> +%.o: Makefile
>> +
>> +$(TARGET): test-mem-claim.o
>> +	$(CC) -o $@ $< $(LDFLAGS)
>> +
>> +-include $(DEPS_INCLUDE)
>> diff --git a/tools/tests/mem-claim/test-mem-claim.c b/tools/tests/mem-claim/test-mem-claim.c
>> new file mode 100644
>> index 000000000000..78eae9091f52
>> --- /dev/null
>> +++ b/tools/tests/mem-claim/test-mem-claim.c
>> @@ -0,0 +1,190 @@
> SPDX header comment?

Will do.

>
>> +#include <err.h>
>> +#include <errno.h>
>> +#include <inttypes.h>
>> +#include <stdio.h>
>> +#include <string.h>
>> +#include <sys/mman.h>
>> +
>> +#include <xenctrl.h>
>> +#include <xenforeignmemory.h>
>> +#include <xengnttab.h>
>> +#include <xen-tools/common-macros.h>
>> +
>> +static unsigned int nr_failures;
>> +#define fail(fmt, ...)                          \
>> +({                                              \
>> +    nr_failures++;                              \
>> +    (void)printf(fmt, ##__VA_ARGS__);           \
>> +})
>> +
>> +static xc_interface *xch;
>> +static uint32_t domid = -1;
> I think you could use domid_t and DOMID_INVALID as the default value?

Sadly can't.  Domid's are strictly uint32_t due to xc_domain_create()
taking it by pointer.

> And then you could avoid the casting and just use domid <
> DOMID_FIRST_RESERVED as the check for whether the cleanup is needed?

Hmm.  The DOMID_INVALID part of that is nice-ish, but having the
boundary check be a different constant isn't.

Maybe I can just do != DOMID_INVALID for the cleanup.

>
>> +
>> +static xc_physinfo_t physinfo;
>> +
>> +static struct xen_domctl_createdomain create = {
>> +    .flags = XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap,
>> +    .max_vcpus = 1,
>> +    .max_grant_frames = 1,
>> +    .grant_opts = XEN_DOMCTL_GRANT_version(1),
>> +
>> +    .arch = {
>> +#if defined(__x86_64__) || defined(__i386__)
>> +        .emulation_flags = XEN_X86_EMU_LAPIC,
>> +#endif
>> +    },
>> +};
>> +
>> +static void run_tests(void)
>> +{
>> +    int rc;
>> +
>> +    /*
>> +     * Check that the system is quiescent.  Outstanding claims is a global
>> +     * field.
>> +     */
>> +    rc = xc_physinfo(xch, &physinfo);
>> +    if ( rc )
>> +        return fail("Failed to obtain physinfo: %d - %s\n",
>> +                    errno, strerror(errno));
>> +
>> +    printf("Free pages: %"PRIu64", Oustanding claims: %"PRIu64"\n",
>> +           physinfo.free_pages, physinfo.outstanding_pages);
>> +
>> +    if ( physinfo.outstanding_pages )
>> +        return fail("  Test needs running on a quiescent system\n");
>> +
>> +    /*
>> +     * We want any arbitrary domain.  Start with HVM/HAP, falling back to
>> +     * HVM/Shadow and then to PV.  The dom0 running this test case is one of
>> +     * these modes.
>> +     */
>> +#if defined(__x86_64__) || defined(__i386__)
>> +    if ( !(physinfo.capabilities & XEN_SYSCTL_PHYSCAP_hap) )
>> +        create.flags &= ~XEN_DOMCTL_CDF_hap;
>> +
>> +    if ( !(physinfo.capabilities & (XEN_SYSCTL_PHYSCAP_hap|XEN_SYSCTL_PHYSCAP_shadow)) ||
>> +         !(physinfo.capabilities & XEN_SYSCTL_PHYSCAP_hvm) )
>> +    {
>> +        create.flags &= ~XEN_DOMCTL_CDF_hvm;
>> +        create.arch.emulation_flags = 0;
>> +    }
>> +#endif
>> +
>> +    rc = xc_domain_create(xch, &domid, &create);
>> +    if ( rc )
>> +        return fail("  Domain create failure: %d - %s\n",
>> +                    errno, strerror(errno));
>> +
>> +    rc = xc_domain_setmaxmem(xch, domid, -1);
>> +    if ( rc )
>> +        return fail("  Failed to set maxmem: %d - %s\n",
>> +                    errno, strerror(errno));
>> +
>> +    printf("  Created d%u\n", domid);
>> +
>> +    /*
>> +     * Creating a domain shouldn't change the claim.  Check it's still 0.
>> +     */
>> +    rc = xc_physinfo(xch, &physinfo);
>> +    if ( rc )
>> +        return fail("  Failed to obtain physinfo: %d - %s\n",
>> +                    errno, strerror(errno));
>> +
>> +    if ( physinfo.outstanding_pages )
>> +        return fail("  Unexpected outstanding claim of %"PRIu64" pages\n",
>> +                    physinfo.outstanding_pages);
>> +
>> +    /*
>> +     * Set a claim for 4M.  This should be the only claim in the system, and
>> +     * show up globally.
>> +     */
>> +    rc = xc_domain_claim_pages(xch, domid, 4*1024*1024/4096);
> You can use MB(4) (macro is in tools/common-macros.h) I think for
> clarity?  Same below with MB(2).

I'll wrap it as MB_TO_PAGES() to hide the divide by 4k.

~Andrew