Re: [kvm-unit-tests RFC 2/2] s390x: mvpg: Add SIE mvpg test

[Janosch Frank <frankja@linux.ibm.com>]

On 5/25/21 7:37 PM, Claudio Imbrenda wrote:
> On Thu, 20 May 2021 09:47:30 +0000
> Janosch Frank <frankja@linux.ibm.com> wrote:
> 
>> Let's also check the PEI values to make sure our VSIE implementation
>> is correct.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>>  s390x/Makefile                  |   3 +-
>>  s390x/mvpg-sie.c                | 139
>> ++++++++++++++++++++++++++++++++ s390x/snippets/c/mvpg-snippet.c |
>> 33 ++++++++ s390x/unittests.cfg             |   3 +
>>  4 files changed, 177 insertions(+), 1 deletion(-)
>>  create mode 100644 s390x/mvpg-sie.c
>>  create mode 100644 s390x/snippets/c/mvpg-snippet.c
>>
>> diff --git a/s390x/Makefile b/s390x/Makefile
>> index fe267011..6692cf73 100644
>> --- a/s390x/Makefile
>> +++ b/s390x/Makefile
>> @@ -22,6 +22,7 @@ tests += $(TEST_DIR)/uv-guest.elf
>>  tests += $(TEST_DIR)/sie.elf
>>  tests += $(TEST_DIR)/mvpg.elf
>>  tests += $(TEST_DIR)/uv-host.elf
>> +tests += $(TEST_DIR)/mvpg-sie.elf
>>  
>>  tests_binary = $(patsubst %.elf,%.bin,$(tests))
>>  ifneq ($(HOST_KEY_DOCUMENT),)
>> @@ -79,7 +80,7 @@ FLATLIBS = $(libcflat)
>>  SNIPPET_DIR = $(TEST_DIR)/snippets
>>  
>>  # C snippets that need to be linked
>> -snippets-c =
>> +snippets-c = $(SNIPPET_DIR)/c/mvpg-snippet.gbin
>>  
>>  # ASM snippets that are directly compiled and converted to a *.gbin
>>  snippets-a =
>> diff --git a/s390x/mvpg-sie.c b/s390x/mvpg-sie.c
>> new file mode 100644
>> index 00000000..a617704b
>> --- /dev/null
>> +++ b/s390x/mvpg-sie.c
>> @@ -0,0 +1,139 @@
>> +#include <libcflat.h>
>> +#include <asm/asm-offsets.h>
>> +#include <asm-generic/barrier.h>
>> +#include <asm/interrupt.h>
>> +#include <asm/pgtable.h>
>> +#include <mmu.h>
>> +#include <asm/page.h>
>> +#include <asm/facility.h>
>> +#include <asm/mem.h>
>> +#include <asm/sigp.h>
>> +#include <smp.h>
>> +#include <alloc_page.h>
>> +#include <bitops.h>
>> +#include <vm.h>
>> +#include <sclp.h>
>> +#include <sie.h>
>> +
>> +static u8 *guest;
>> +static u8 *guest_instr;
>> +static struct vm vm;
>> +
>> +static uint8_t *src;
>> +static uint8_t *dst;
>> +
>> +extern const char _binary_s390x_snippets_c_mvpg_snippet_gbin_start[];
>> +extern const char _binary_s390x_snippets_c_mvpg_snippet_gbin_end[];
>> +int binary_size;
>> +
>> +static void handle_validity(struct vm *vm)
>> +{
>> +	report(0, "VALIDITY: %x", vm->sblk->ipb >> 16);
> 
> I think an assert would be better. This should not happen, and if it
> happens something went very wrong and we have no guarantee that we will
> be able to continue

That depends on the test. If you use multiple gbins/snippets in a test,
then a validity for one of those does not necessarily break the others.
Especially when you think about PV tests where the destroy will clean
out all the state anyway.

> 
>> +}
>> +
>> +static void sie(struct vm *vm)
>> +{
>> +	/* Reset icptcode so we don't trip below */
>> +	vm->sblk->icptcode = 0;
>> +
>> +	while (vm->sblk->icptcode == 0) {
>> +		sie64a(vm->sblk, &vm->save_area);
>> +		if (vm->sblk->icptcode == ICPT_VALIDITY)
>> +			handle_validity(vm);
>> +	}
>> +	vm->save_area.guest.grs[14] = vm->sblk->gg14;
>> +	vm->save_area.guest.grs[15] = vm->sblk->gg15;
>> +}
>> +
>> +static void test_mvpg_pei(void)
>> +{
>> +	uint64_t **pei_dst = (uint64_t **)((uintptr_t) vm.sblk +
>> 0xc0);
>> +	uint64_t **pei_src = (uint64_t **)((uintptr_t) vm.sblk +
>> 0xc8); +
>> +	report_prefix_push("pei");
> 
> maybe clear the destination buffer...
> 
>> +	protect_page(guest + 0x6000, PAGE_ENTRY_I);
>> +	sie(&vm);
>> +	report(vm.sblk->icptcode == ICPT_PARTEXEC, "Partial
>> execution");
>> +	report((uintptr_t)**pei_src == ((uintptr_t)vm.sblk->mso) +
>> 0x6000 + PAGE_ENTRY_I, "PEI_SRC correct");
>> +	report((uintptr_t)**pei_dst == vm.sblk->mso + 0x5000,
>> "PEI_DST correct");
> 
> ... and check that the page was not copied

Sure

> 
>> +	/* Jump over the diag44 */
>> +	sie(&vm);
> 
> I would check if you really got a diag44

Sure, reporting doesn't make sense to me but an assert should  be fine

> 
>> +	/* Clear PEI data for next check */
>> +	memset((uint64_t *)((uintptr_t) vm.sblk + 0xc0), 0, 16);
>> +	unprotect_page(guest + 0x6000, PAGE_ENTRY_I);
>> +	protect_page(guest + 0x5000, PAGE_ENTRY_I);
>> +	sie(&vm);
>> +	report(vm.sblk->icptcode == ICPT_PARTEXEC, "Partial
>> execution");
>> +	report((uintptr_t)**pei_src == vm.sblk->mso + 0x6000,
>> "PEI_SRC correct");
>> +	report((uintptr_t)**pei_dst == vm.sblk->mso + 0x5000 +
>> PAGE_ENTRY_I, "PEI_DST correct"); +
>> +	report_prefix_pop();
>> +}
>> +
>> +static void test_mvpg(void)
>> +{
>> +	int binary_size =
>> ((uintptr_t)_binary_s390x_snippets_c_mvpg_snippet_gbin_end -
>> +
>> (uintptr_t)_binary_s390x_snippets_c_mvpg_snippet_gbin_start); +
>> +	memcpy(guest,
>> _binary_s390x_snippets_c_mvpg_snippet_gbin_start, binary_size);
>> +	memset(src, 0x42, PAGE_SIZE);
>> +	memset(dst, 0x43, PAGE_SIZE);
>> +	sie(&vm);
>> +	mb();
>> +	report(!memcmp(src, dst, PAGE_SIZE) && *dst == 0x42, "Page
> 
> or maybe you can clear the destination buffer here, if you prefer

I'll have a look, thanks for the review!

> 
>> moved"); +}
>> +
>> +static void setup_guest(void)
>> +{
>> +	setup_vm();
>> +
>> +	/* Allocate 1MB as guest memory */
>> +	guest = alloc_pages(8);
>> +	/* The first two pages are the lowcore */
>> +	guest_instr = guest + PAGE_SIZE * 2;
>> +
>> +	vm.sblk = alloc_page();
>> +
>> +	vm.sblk->cpuflags = CPUSTAT_ZARCH | CPUSTAT_RUNNING;
>> +	vm.sblk->prefix = 0;
>> +	/*
>> +	 * Pageable guest with the same ASCE as the test programm,
>> but
>> +	 * the guest memory 0x0 is offset to start at the allocated
>> +	 * guest pages and end after 1MB.
>> +	 *
>> +	 * It's not pretty but faster and easier than managing guest
>> ASCEs.
>> +	 */
>> +	vm.sblk->mso = (u64)guest;
>> +	vm.sblk->msl = (u64)guest;
>> +	vm.sblk->ihcpu = 0xffff;
>> +
>> +	vm.sblk->crycbd = (uint64_t)alloc_page();
>> +
>> +	vm.sblk->gpsw.addr = PAGE_SIZE * 4;
>> +	vm.sblk->gpsw.mask = 0x0000000180000000ULL;
>> +	vm.sblk->ictl = ICTL_OPEREXC | ICTL_PINT;
>> +	/* Enable MVPG interpretation as we want to test KVM and not
>> ourselves */
>> +	vm.sblk->eca = ECA_MVPGI;
>> +
>> +	src = guest + PAGE_SIZE * 6;
>> +	dst = guest + PAGE_SIZE * 5;
>> +}
>> +
>> +int main(void)
>> +{
>> +	report_prefix_push("mvpg-sie");
>> +	if (!sclp_facilities.has_sief2) {
>> +		report_skip("SIEF2 facility unavailable");
>> +		goto done;
>> +	}
>> +
>> +	setup_guest();
>> +	test_mvpg();
>> +	test_mvpg_pei();
>> +
>> +done:
>> +	report_prefix_pop();
>> +	return report_summary();
>> +
>> +}
>> diff --git a/s390x/snippets/c/mvpg-snippet.c
>> b/s390x/snippets/c/mvpg-snippet.c new file mode 100644
>> index 00000000..96b70c9c
>> --- /dev/null
>> +++ b/s390x/snippets/c/mvpg-snippet.c
>> @@ -0,0 +1,33 @@
>> +#include <libcflat.h>
>> +
>> +static inline void force_exit(void)
>> +{
>> +	asm volatile("	diag	0,0,0x44\n");
>> +}
>> +
>> +static inline int mvpg(unsigned long r0, void *dest, void *src)
>> +{
>> +	register unsigned long reg0 asm ("0") = r0;
>> +	int cc;
>> +
>> +	asm volatile("	mvpg    %1,%2\n"
>> +		     "	ipm     %0\n"
>> +		     "	srl     %0,28"
>> +		     : "=&d" (cc) : "a" (dest), "a" (src), "d" (reg0)
>> +		     : "memory", "cc");
>> +	return cc;
>> +}
>> +
>> +static void test_mvpg_real(void)
>> +{
>> +	mvpg(0, (void *)0x5000, (void *)0x6000);
>> +	force_exit();
>> +}
>> +
>> +__attribute__((section(".text"))) int main(void)
>> +{
>> +	test_mvpg_real();
>> +	test_mvpg_real();
>> +	test_mvpg_real();
>> +	return 0;
>> +}
>> diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
>> index 9f81a608..8634b1b1 100644
>> --- a/s390x/unittests.cfg
>> +++ b/s390x/unittests.cfg
>> @@ -103,3 +103,6 @@ file = sie.elf
>>  [mvpg]
>>  file = mvpg.elf
>>  timeout = 10
>> +
>> +[mvpg-sie]
>> +file = mvpg-sie.elf
>