Re: [kvm-unit-tests PATCH 2/3] s390x: Test TEID values in storage key test

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Thu,  5 May 2022 14:46:55 +0200
Janis Schoetterl-Glausch <scgl@linux.ibm.com> wrote:

> On a protection exception, test that the Translation-Exception
> Identification (TEID) values are correct given the circumstances of the
> particular test.
> The meaning of the TEID values is dependent on the installed
> suppression-on-protection facility.
> 
> Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
> ---
>  lib/s390x/asm/facility.h | 21 ++++++++++++++
>  lib/s390x/sclp.h         |  2 ++
>  lib/s390x/sclp.c         |  2 ++
>  s390x/skey.c             | 60 ++++++++++++++++++++++++++++++++++++----
>  4 files changed, 79 insertions(+), 6 deletions(-)
> 
> diff --git a/lib/s390x/asm/facility.h b/lib/s390x/asm/facility.h
> index ef0fd037..f21bb9d7 100644
> --- a/lib/s390x/asm/facility.h
> +++ b/lib/s390x/asm/facility.h
> @@ -12,6 +12,7 @@
>  #include <asm/facility.h>
>  #include <asm/arch_def.h>
>  #include <bitops.h>
> +#include <sclp.h>
>  
>  #define NB_STFL_DOUBLEWORDS 32
>  extern uint64_t stfl_doublewords[];
> @@ -44,4 +45,24 @@ static inline void setup_facilities(void)
>  		stfle(stfl_doublewords, NB_STFL_DOUBLEWORDS);
>  }
>  
> +enum supp_on_prot_facility {
> +	SOP_NONE,
> +	SOP_BASIC,
> +	SOP_ENHANCED_1,
> +	SOP_ENHANCED_2,
> +};
> +
> +static inline enum supp_on_prot_facility get_supp_on_prot_facility(void)
> +{
> +	if (sclp_facilities.has_esop) {
> +		if (test_facility(131)) /* side-effect-access facility */
> +			return SOP_ENHANCED_2;
> +		else
> +			return SOP_ENHANCED_1;
> +	}
> +	if (sclp_facilities.has_sop)
> +		return SOP_BASIC;
> +	return SOP_NONE;
> +}
> +
>  #endif
> diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
> index 4ce2209f..f57896b2 100644
> --- a/lib/s390x/sclp.h
> +++ b/lib/s390x/sclp.h
> @@ -123,7 +123,9 @@ struct sclp_facilities {
>  	uint64_t has_cei : 1;
>  
>  	uint64_t has_diag318 : 1;
> +	uint64_t has_sop : 1;
>  	uint64_t has_gsls : 1;
> +	uint64_t has_esop : 1;
>  	uint64_t has_cmma : 1;
>  	uint64_t has_64bscao : 1;
>  	uint64_t has_esca : 1;
> diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
> index b8204c5f..e6017f64 100644
> --- a/lib/s390x/sclp.c
> +++ b/lib/s390x/sclp.c
> @@ -152,7 +152,9 @@ void sclp_facilities_setup(void)
>  	cpu = sclp_get_cpu_entries();
>  	if (read_info->offset_cpu > 134)
>  		sclp_facilities.has_diag318 = read_info->byte_134_diag318;
> +	sclp_facilities.has_sop = sclp_feat_check(80, SCLP_FEAT_80_BIT_SOP);
>  	sclp_facilities.has_gsls = sclp_feat_check(85, SCLP_FEAT_85_BIT_GSLS);
> +	sclp_facilities.has_esop = sclp_feat_check(85, SCLP_FEAT_85_BIT_ESOP);
>  	sclp_facilities.has_kss = sclp_feat_check(98, SCLP_FEAT_98_BIT_KSS);
>  	sclp_facilities.has_cmma = sclp_feat_check(116, SCLP_FEAT_116_BIT_CMMA);
>  	sclp_facilities.has_64bscao = sclp_feat_check(116, SCLP_FEAT_116_BIT_64BSCAO);
> diff --git a/s390x/skey.c b/s390x/skey.c
> index 32bf1070..56bf5f45 100644
> --- a/s390x/skey.c
> +++ b/s390x/skey.c
> @@ -8,6 +8,7 @@
>   *  Janosch Frank <frankja@linux.vnet.ibm.com>
>   */
>  #include <libcflat.h>
> +#include <bitops.h>
>  #include <asm/asm-offsets.h>
>  #include <asm/interrupt.h>
>  #include <vmalloc.h>
> @@ -158,6 +159,53 @@ static void test_test_protection(void)
>  	report_prefix_pop();
>  }
>  
> +enum access {
> +	ACC_FETCH = 2,
> +	ACC_STORE = 1,
> +	ACC_UPDATE = 3,
> +};

why not in numerical order?

> +
> +enum protection {
> +	PROT_STORE = 1,
> +	PROT_FETCH_STORE = 3,
> +};

what happened to 2?

> +
> +static void check_key_prot_exc(enum access access, enum protection prot)
> +{
> +	struct lowcore *lc = 0;
> +	union teid teid;
> +
> +	check_pgm_int_code(PGM_INT_CODE_PROTECTION);
> +	report_prefix_push("TEID");
> +	teid.val = lc->trans_exc_id;
> +	switch (get_supp_on_prot_facility()) {
> +	case SOP_NONE:
> +	case SOP_BASIC:
> +		break;
> +	case SOP_ENHANCED_1:
> +		if ((teid.val & (BIT(63 - 61))) == 0)

why not teid.m?

> +			report_pass("key-controlled protection");
> +		break;
> +	case SOP_ENHANCED_2:
> +		if ((teid.val & (BIT(63 - 56) | BIT(63 - 61))) == 0) {

maybe here you need to expand struct teid a little to accomodate for
bit 56.

> +			report_pass("key-controlled protection");
> +			if (teid.val & BIT(63 - 60)) {
> +				int access_code = teid.fetch << 1 | teid.store;
> +
> +				report_info("access code: %d", access_code);

I don't like an unconditional report_info (it's ok to aid debugging if
something fails)

> +				if (access_code == 2)
> +					report((access & 2) && (prot & 2),
> +					       "exception due to fetch");
> +				if (access_code == 1)
> +					report((access & 1) && (prot & 1),
> +					       "exception due to store");

what about cases 0 and 3?
if they should never happen, handle it properly
and if they can happen... handle it properly

> +			}
> +		}
> +		break;
> +	}
> +	report_prefix_pop();
> +}
> +
>  /*
>   * Perform STORE CPU ADDRESS (STAP) instruction while temporarily executing
>   * with access key 1.
> @@ -199,7 +247,7 @@ static void test_store_cpu_address(void)
>  	expect_pgm_int();
>  	*out = 0xbeef;
>  	store_cpu_address_key_1(out);
> -	check_pgm_int_code(PGM_INT_CODE_PROTECTION);
> +	check_key_prot_exc(ACC_STORE, PROT_STORE);
>  	report(*out == 0xbeef, "no store occurred");
>  	report_prefix_pop();
>  
> @@ -210,7 +258,7 @@ static void test_store_cpu_address(void)
>  	expect_pgm_int();
>  	*out = 0xbeef;
>  	store_cpu_address_key_1(out);
> -	check_pgm_int_code(PGM_INT_CODE_PROTECTION);
> +	check_key_prot_exc(ACC_STORE, PROT_STORE);
>  	report(*out == 0xbeef, "no store occurred");
>  	report_prefix_pop();
>  
> @@ -228,7 +276,7 @@ static void test_store_cpu_address(void)
>  	expect_pgm_int();
>  	*out = 0xbeef;
>  	store_cpu_address_key_1(out);
> -	check_pgm_int_code(PGM_INT_CODE_PROTECTION);
> +	check_key_prot_exc(ACC_STORE, PROT_STORE);
>  	report(*out == 0xbeef, "no store occurred");
>  	report_prefix_pop();
>  
> @@ -314,7 +362,7 @@ static void test_set_prefix(void)
>  	set_storage_key(pagebuf, 0x28, 0);
>  	expect_pgm_int();
>  	set_prefix_key_1(prefix_ptr);
> -	check_pgm_int_code(PGM_INT_CODE_PROTECTION);
> +	check_key_prot_exc(ACC_FETCH, PROT_FETCH_STORE);
>  	report(get_prefix() == old_prefix, "did not set prefix");
>  	report_prefix_pop();
>  
> @@ -327,7 +375,7 @@ static void test_set_prefix(void)
>  	install_page(root, virt_to_pte_phys(root, pagebuf), 0);
>  	set_prefix_key_1((uint32_t *)0);
>  	install_page(root, 0, 0);
> -	check_pgm_int_code(PGM_INT_CODE_PROTECTION);
> +	check_key_prot_exc(ACC_FETCH, PROT_FETCH_STORE);
>  	report(get_prefix() == old_prefix, "did not set prefix");
>  	report_prefix_pop();
>  
> @@ -351,7 +399,7 @@ static void test_set_prefix(void)
>  	install_page(root, virt_to_pte_phys(root, pagebuf), 0);
>  	set_prefix_key_1((uint32_t *)2048);
>  	install_page(root, 0, 0);
> -	check_pgm_int_code(PGM_INT_CODE_PROTECTION);
> +	check_key_prot_exc(ACC_FETCH, PROT_FETCH_STORE);
>  	report(get_prefix() == old_prefix, "did not set prefix");
>  	report_prefix_pop();
>