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[46.114.147.107]) by smtp.gmail.com with ESMTPSA id z17sm8947066wrt.47.2021.08.06.01.22.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 06 Aug 2021 01:22:57 -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> From: Thomas Huth Message-ID: <653d280b-98db-91d1-d21a-e6c07aacc972@redhat.com> Date: Fri, 6 Aug 2021 10:22:55 +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=ham 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 10.20, 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 ? Thomas