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Thu, 7 Jul 2022 09:19:14 +0000 (GMT) Received: from p-imbrenda (unknown [9.152.224.40]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 7 Jul 2022 09:19:14 +0000 (GMT) Date: Thu, 7 Jul 2022 11:19:12 +0200 From: Claudio Imbrenda To: Janosch Frank Cc: kvm390 mailing list , kvm@vger.kernel.org, linux-s390@vger.kernel.org, thuth@redhat.com, seiden@linux.ibm.com, nrb@linux.ibm.com, scgl@linux.ibm.com Subject: Re: [kvm-unit-tests PATCH v2 1/8] s390x: uv-host: Add access checks for donated memory Message-ID: <20220707111912.51ecc0f2@p-imbrenda> In-Reply-To: References: <20220706064024.16573-1-frankja@linux.ibm.com> <20220706064024.16573-2-frankja@linux.ibm.com> <20220706183346.2a027e8b@p-imbrenda> Organization: IBM X-Mailer: Claws Mail 4.1.0 (GTK 3.24.34; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: VsdMDxXH4ElbAsLfBWsgfht4-baj5fN- X-Proofpoint-ORIG-GUID: aGcy7AJCDohDTC_JAVV8lE2BPzLNLKWX X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-07-07_06,2022-06-28_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 spamscore=0 bulkscore=0 adultscore=0 priorityscore=1501 clxscore=1015 suspectscore=0 phishscore=0 mlxlogscore=999 malwarescore=0 impostorscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2206140000 definitions=main-2207070036 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Thu, 7 Jul 2022 10:16:44 +0200 Janosch Frank wrote: > On 7/6/22 18:33, Claudio Imbrenda wrote: > > On Wed, 6 Jul 2022 06:40:17 +0000 > > Janosch Frank wrote: > > > >> Let's check if the UV really protected all the memory we donated. > >> > >> Signed-off-by: Janosch Frank > >> --- > >> s390x/uv-host.c | 29 +++++++++++++++++++++++++++++ > >> 1 file changed, 29 insertions(+) > >> > >> diff --git a/s390x/uv-host.c b/s390x/uv-host.c > >> index a1a6d120..983cb4a1 100644 > >> --- a/s390x/uv-host.c > >> +++ b/s390x/uv-host.c > >> @@ -43,6 +43,24 @@ static void cpu_loop(void) > >> for (;;) {} > >> } > >> > >> +/* > >> + * Checks if a memory area is protected as secure memory. > >> + * Will return true if all pages are protected, false otherwise. > >> + */ > >> +static bool access_check_3d(uint64_t *access_ptr, uint64_t len) > >> +{ > >> + while (len) { > >> + expect_pgm_int(); > >> + *access_ptr += 42; > > > > I'm surprised this works, you will get an (expected) exception when > > reading from the pointer, and then you should get another one (at this > > point unexpected) when writing > > > > Let me introduce you to "AGSI" add grand storage immediate. wow, of course there is an instruction for that :D > But I get your point, inline assembly would make this much more explicit. actually, I think you should separately check for read and write access. something like expect_pgm_int(); READ_ONCE(*access_ptr); ... expect_pgm_int(); WRITE_ONCE(*access_ptr, 42); to really make sure both read and write access are blocked > > >> + if (clear_pgm_int() != PGM_INT_CODE_SECURE_STOR_ACCESS) > >> + return false; > >> + access_ptr += PAGE_SIZE / sizeof(access_ptr); > >> + len -= PAGE_SIZE; > >> + } > >> + > >> + return true; > >> +} > >> + > >> static struct cmd_list cmds[] = { > >> { "init", UVC_CMD_INIT_UV, sizeof(struct uv_cb_init), BIT_UVC_CMD_INIT_UV }, > >> { "create conf", UVC_CMD_CREATE_SEC_CONF, sizeof(struct uv_cb_cgc), BIT_UVC_CMD_CREATE_SEC_CONF }, > >> @@ -194,6 +212,10 @@ static void test_cpu_create(void) > >> report(rc == 0 && uvcb_csc.header.rc == UVC_RC_EXECUTED && > >> uvcb_csc.cpu_handle, "success"); > >> > >> + rc = access_check_3d((uint64_t *)uvcb_csc.stor_origin, > >> + uvcb_qui.cpu_stor_len); > >> + report(rc, "Storage protection"); > >> + > >> tmp = uvcb_csc.stor_origin; > >> uvcb_csc.stor_origin = (unsigned long)memalign(PAGE_SIZE, uvcb_qui.cpu_stor_len); > >> rc = uv_call(0, (uint64_t)&uvcb_csc); > >> @@ -292,6 +314,13 @@ static void test_config_create(void) > >> rc = uv_call(0, (uint64_t)&uvcb_cgc); > >> report(rc == 0 && uvcb_cgc.header.rc == UVC_RC_EXECUTED, "successful"); > >> > >> + rc = access_check_3d((uint64_t *)uvcb_cgc.conf_var_stor_origin, vsize); > >> + report(rc, "Base storage protection"); > >> + > >> + rc = access_check_3d((uint64_t *)uvcb_cgc.conf_base_stor_origin, > >> + uvcb_qui.conf_base_phys_stor_len); > >> + report(rc, "Variable storage protection"); > >> + > >> uvcb_cgc.header.rc = 0; > >> uvcb_cgc.header.rrc = 0; > >> tmp = uvcb_cgc.guest_handle; > > >