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[46.114.147.107]) by smtp.gmail.com with ESMTPSA id e6sm7693908wme.6.2021.08.06.01.24.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 06 Aug 2021 01:24:50 -0700 (PDT) Subject: Re: [PATCH v1 07/12] s390x/mmu_helper: move address validation into mmu_translate*() To: David Hildenbrand , qemu-devel@nongnu.org References: <20210805152804.100333-1-david@redhat.com> <20210805152804.100333-8-david@redhat.com> <6616c45b-7d5a-3a8f-20fb-0c17113e49b1@redhat.com> <653d280b-98db-91d1-d21a-e6c07aacc972@redhat.com> From: Thomas Huth Message-ID: <8e109972-bcb9-5f53-d6d2-dc2e913985ae@redhat.com> Date: Fri, 6 Aug 2021 10:24:49 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=thuth@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.699, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.132, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Jason J . Herne" , Janosch Frank , Cornelia Huck , Richard Henderson , Halil Pasic , Christian Borntraeger , qemu-s390x@nongnu.org, Claudio Imbrenda Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 06/08/2021 10.23, David Hildenbrand wrote: > On 06.08.21 10:22, Thomas Huth wrote: >> On 06/08/2021 10.20, David Hildenbrand wrote: >>> On 06.08.21 10:18, Thomas Huth wrote: >>>> On 05/08/2021 17.27, David Hildenbrand wrote: >>>>> Let's move address validation into mmu_translate() and >>>>> mmu_translate_real(). This allows for checking whether an absolute >>>>> address is valid before looking up the storage key. We can now get rid of >>>>> the ram_size check. >>>>> >>>>> Interestingly, we're already handling LOAD REAL ADDRESS wrong, because >>>>> a) We're not supposed to touch storage keys >>>>> b) We're not supposed to convert to an absolute address >>>>> >>>>> Let's use a fake, negative MMUAccessType to teach mmu_translate() to >>>>> fix that handling and to not perform address validation. >>>>> >>>>> Signed-off-by: David Hildenbrand >>>>> --- >>>>>     target/s390x/mmu_helper.c      | 36 ++++++++++++++++++++-------------- >>>>>     target/s390x/tcg/excp_helper.c | 13 ------------ >>>>>     target/s390x/tcg/mem_helper.c  |  2 +- >>>>>     3 files changed, 22 insertions(+), 29 deletions(-) >>>>> >>>>> diff --git a/target/s390x/mmu_helper.c b/target/s390x/mmu_helper.c >>>>> index ca25dadb5b..36ab4e9c81 100644 >>>>> --- a/target/s390x/mmu_helper.c >>>>> +++ b/target/s390x/mmu_helper.c >>>>> @@ -301,14 +301,13 @@ static void mmu_handle_skey(target_ulong addr, int >>>>> rw, int *flags) >>>>>     { >>>>>         static S390SKeysClass *skeyclass; >>>>>         static S390SKeysState *ss; >>>>> -    MachineState *ms = MACHINE(qdev_get_machine()); >>>>>         uint8_t key; >>>>>         int rc; >>>>> -    if (unlikely(addr >= ms->ram_size)) { >>>>> -        return; >>>>> -    } >>>>> - >>>>> +    /* >>>>> +     * We excpect to be called with an absolute address that has already >>>>> been >>>>> +     * validated, such that we can reliably use it to lookup the storage >>>>> key. >>>>> +     */ >>>>>         if (unlikely(!ss)) { >>>>>             ss = s390_get_skeys_device(); >>>>>             skeyclass = S390_SKEYS_GET_CLASS(ss); >>>>> @@ -370,7 +369,7 @@ static void mmu_handle_skey(target_ulong addr, int >>>>> rw, int *flags) >>>>>     /** >>>>>      * Translate a virtual (logical) address into a physical (absolute) >>>>> address. >>>>>      * @param vaddr  the virtual address >>>>> - * @param rw     0 = read, 1 = write, 2 = code fetch >>>>> + * @param rw     0 = read, 1 = write, 2 = code fetch, < 0 = load real >>>>> address >>>>>      * @param asc    address space control (one of the PSW_ASC_* modes) >>>>>      * @param raddr  the translated address is stored to this pointer >>>>>      * @param flags  the PAGE_READ/WRITE/EXEC flags are stored to this >>>>> pointer >>>>> @@ -449,10 +448,17 @@ int mmu_translate(CPUS390XState *env, target_ulong >>>>> vaddr, int rw, uint64_t asc, >>>>>         } >>>>>     nodat: >>>>> -    /* Convert real address -> absolute address */ >>>>> -    *raddr = mmu_real2abs(env, *raddr); >>>>> +    if (rw >= 0) { >>>>> +        /* Convert real address -> absolute address */ >>>>> +        *raddr = mmu_real2abs(env, *raddr); >>>>> -    mmu_handle_skey(*raddr, rw, flags); >>>>> +        if (!mmu_absolute_addr_valid(*raddr, rw == MMU_DATA_STORE)) { >>>>> +            *tec = 0; /* unused */ >>>>> +            return PGM_ADDRESSING; >>>>> +        } >>>>> + >>>>> +        mmu_handle_skey(*raddr, rw, flags); >>>>> +    } >>>>>         return 0; >>>>>     } >>>>> @@ -473,12 +479,6 @@ static int translate_pages(S390CPU *cpu, vaddr addr, >>>>> int nr_pages, >>>>>             if (ret) { >>>>>                 return ret; >>>>>             } >>>>> -        if (!address_space_access_valid(&address_space_memory, pages[i], >>>>> -                                        TARGET_PAGE_SIZE, is_write, >>>>> -                                        MEMTXATTRS_UNSPECIFIED)) { >>>>> -            *tec = 0; /* unused */ >>>>> -            return PGM_ADDRESSING; >>>>> -        } >>>>>             addr += TARGET_PAGE_SIZE; >>>>>         } >>>>> @@ -588,6 +588,12 @@ int mmu_translate_real(CPUS390XState *env, >>>>> target_ulong raddr, int rw, >>>>>         *addr = mmu_real2abs(env, raddr & TARGET_PAGE_MASK); >>>>> +    if (!mmu_absolute_addr_valid(*addr, rw == MMU_DATA_STORE)) { >>>>> +        /* unused */ >>>>> +        *tec = 0; >>>>> +        return PGM_ADDRESSING; >>>>> +    } >>>>> + >>>>>         mmu_handle_skey(*addr, rw, flags); >>>>>         return 0; >>>>>     } >>>>> diff --git a/target/s390x/tcg/excp_helper.c >>>>> b/target/s390x/tcg/excp_helper.c >>>>> index a61917d04f..3d6662a53c 100644 >>>>> --- a/target/s390x/tcg/excp_helper.c >>>>> +++ b/target/s390x/tcg/excp_helper.c >>>>> @@ -150,19 +150,6 @@ bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, >>>>> int size, >>>>>             g_assert_not_reached(); >>>>>         } >>>>> -    /* check out of RAM access */ >>>>> -    if (!excp && >>>>> -        !address_space_access_valid(&address_space_memory, raddr, >>>>> -                                    TARGET_PAGE_SIZE, access_type, >>>>> -                                    MEMTXATTRS_UNSPECIFIED)) { >>>>> -        MachineState *ms = MACHINE(qdev_get_machine()); >>>>> -        qemu_log_mask(CPU_LOG_MMU, >>>>> -                      "%s: raddr %" PRIx64 " > ram_size %" PRIx64 "\n", >>>>> -                      __func__, (uint64_t)raddr, (uint64_t)ms->ram_size); >>>>> -        excp = PGM_ADDRESSING; >>>>> -        tec = 0; /* unused */ >>>>> -    } >>>>> - >>>>>         env->tlb_fill_exc = excp; >>>>>         env->tlb_fill_tec = tec; >>>>> diff --git a/target/s390x/tcg/mem_helper.c b/target/s390x/tcg/mem_helper.c >>>>> index a84795cfa3..9c1b9c7d06 100644 >>>>> --- a/target/s390x/tcg/mem_helper.c >>>>> +++ b/target/s390x/tcg/mem_helper.c >>>>> @@ -2456,7 +2456,7 @@ uint64_t HELPER(lra)(CPUS390XState *env, uint64_t >>>>> addr) >>>>>             tcg_s390_program_interrupt(env, PGM_SPECIAL_OP, GETPC()); >>>>>         } >>>>> -    exc = mmu_translate(env, addr, 0, asc, &ret, &flags, &tec); >>>>> +    exc = mmu_translate(env, addr, -1, asc, &ret, &flags, &tec); >>>> >>>> Do we maybe want a #define for this -1 instead? OTOH, you've added a proper >>>> comment to the function description, so that should be ok, too. >>> >>> Ideally, I'd have used a completely new MMU_* type. But affecting all users >>> in QEMU for one special case and having to handle it consequently >>> accordingly all over the place feels wrong. >>> >>> Where would you put the define? >> >> I agree that this should not go into the common header ... so maybe into >> s390x-internal.h ? > > Maybe calling it MMU_S390_LRA ? Sounds good! Thomas