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Wed, 31 Jul 2024 00:03:17 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFqhGyvdB5DyHe3W381+2OBrcPmLv1DDfOJxLzBkjNCIHRDY9968utATm5TcMH/dNiQM08rBQ== X-Received: by 2002:a17:903:25c5:b0:1fd:5fa0:e99b with SMTP id d9443c01a7336-1ff04932858mr99305825ad.57.1722409397396; Wed, 31 Jul 2024 00:03:17 -0700 (PDT) Received: from [192.168.68.54] ([43.252.112.134]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fed7ee5734sm112968765ad.135.2024.07.31.00.03.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 31 Jul 2024 00:03:16 -0700 (PDT) Message-ID: <3e30f7b8-c7a4-4ab9-8afc-a48c84e62728@redhat.com> Date: Wed, 31 Jul 2024 17:03:07 +1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 03/15] arm64: Detect if in a realm and set RIPAS RAM To: Suzuki K Poulose , Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni References: <20240701095505.165383-1-steven.price@arm.com> <20240701095505.165383-4-steven.price@arm.com> <2b4f0496-99f4-4bc6-af6c-a8be8fca69a8@redhat.com> <7203814a-1a1d-41c4-8fc5-95216e2febcd@arm.com> From: Gavin Shan In-Reply-To: <7203814a-1a1d-41c4-8fc5-95216e2febcd@arm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240731_000323_155557_44393EB8 X-CRM114-Status: GOOD ( 38.78 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Suzuki, On 7/30/24 11:51 PM, Suzuki K Poulose wrote: > On 30/07/2024 00:37, Gavin Shan wrote: >> On 7/1/24 7:54 PM, Steven Price wrote: >>> From: Suzuki K Poulose >>> >>> Detect that the VM is a realm guest by the presence of the RSI >>> interface. >>> >>> If in a realm then all memory needs to be marked as RIPAS RAM initially, >>> the loader may or may not have done this for us. To be sure iterate over >>> all RAM and mark it as such. Any failure is fatal as that implies the >>> RAM regions passed to Linux are incorrect - which would mean failing >>> later when attempting to access non-existent RAM. >>> >>> Signed-off-by: Suzuki K Poulose >>> Co-developed-by: Steven Price >>> Signed-off-by: Steven Price >>> --- >>> Changes since v3: >>>   * Provide safe/unsafe versions for converting memory to protected, >>>     using the safer version only for the early boot. >>>   * Use the new psci_early_test_conduit() function to avoid calling an >>>     SMC if EL3 is not present (or not configured to handle an SMC). >>> Changes since v2: >>>   * Use DECLARE_STATIC_KEY_FALSE rather than "extern struct >>>     static_key_false". >>>   * Rename set_memory_range() to rsi_set_memory_range(). >>>   * Downgrade some BUG()s to WARN()s and handle the condition by >>>     propagating up the stack. Comment the remaining case that ends in a >>>     BUG() to explain why. >>>   * Rely on the return from rsi_request_version() rather than checking >>>     the version the RMM claims to support. >>>   * Rename the generic sounding arm64_setup_memory() to >>>     arm64_rsi_setup_memory() and move the call site to setup_arch(). >>> --- >>>   arch/arm64/include/asm/rsi.h      | 64 +++++++++++++++++++++++++ >>>   arch/arm64/include/asm/rsi_cmds.h | 22 +++++++++ >>>   arch/arm64/kernel/Makefile        |  3 +- >>>   arch/arm64/kernel/rsi.c           | 77 +++++++++++++++++++++++++++++++ >>>   arch/arm64/kernel/setup.c         |  8 ++++ >>>   5 files changed, 173 insertions(+), 1 deletion(-) >>>   create mode 100644 arch/arm64/include/asm/rsi.h >>>   create mode 100644 arch/arm64/kernel/rsi.c >>> >>> diff --git a/arch/arm64/include/asm/rsi.h b/arch/arm64/include/asm/rsi.h >>> new file mode 100644 >>> index 000000000000..29fdc194d27b >>> --- /dev/null >>> +++ b/arch/arm64/include/asm/rsi.h >>> @@ -0,0 +1,64 @@ >>> +/* SPDX-License-Identifier: GPL-2.0-only */ >>> +/* >>> + * Copyright (C) 2024 ARM Ltd. >>> + */ >>> + >>> +#ifndef __ASM_RSI_H_ >>> +#define __ASM_RSI_H_ >>> + >>> +#include >>> +#include >>> + >>> +DECLARE_STATIC_KEY_FALSE(rsi_present); >>> + >>> +void __init arm64_rsi_init(void); >>> +void __init arm64_rsi_setup_memory(void); >>> +static inline bool is_realm_world(void) >>> +{ >>> +    return static_branch_unlikely(&rsi_present); >>> +} >>> + >>> +static inline int rsi_set_memory_range(phys_addr_t start, phys_addr_t end, >>> +                       enum ripas state, unsigned long flags) >>> +{ >>> +    unsigned long ret; >>> +    phys_addr_t top; >>> + >>> +    while (start != end) { >>> +        ret = rsi_set_addr_range_state(start, end, state, flags, &top); >>> +        if (WARN_ON(ret || top < start || top > end)) >>> +            return -EINVAL; >>> +        start = top; >>> +    } >>> + >>> +    return 0; >>> +} >>> + >> >> @flags has been defined as int instead of unsigned long, which is inconsistent >> to TF-RMM's definitions since it has type of 'unsigned long'. > > Sorry, do you mean that TF-RMM treats the "flags" as an "int" instead of > unsigned long and we should be consistent with TF-RMM ? If so, I don't > think that is correct. We should be compliant to the RMM spec, which > describes "RsiRipasChangeFlags" as a 64bit value and thus must be > 'unsigned long' as we used here. > No worries, I guess I didn't make myself clear enough. Sorry about that. Let me explain it with more details. @flag is passed down as the following call trace shows. rsi_set_memory_range_protected_safe rsi_set_memory_range // RSI_NO_CHANGE_DESTROYED rsi_set_addr_range_state arm_smccc_smc(SMC_RSI_IPA_STATE_SET, ...) The kernel defines RSI_CHANGE_DESTROYED as a "int" value, but same flag has been defined as 'unsigned int' value in tf-rmm. However, kernel uses 'unsigned long' flags to hold it. // kernel's prototype - 'unsigned long flags' static inline int rsi_set_memory_range(phys_addr_t start, phys_addr_t end, enum ripas state, unsigned long flags) // kernel's definition - 'int' #define RSI_CHANGE_DESTROYED 0 // tf-rmm's definition - 'unsigned int' #define U(_x) (unsigned int)(_x) #define RSI_CHANGE_DESTROYED U(0) >> >>> +/* >>> + * Convert the specified range to RAM. Do not use this if you rely on the >>> + * contents of a page that may already be in RAM state. >>> + */ >>> +static inline int rsi_set_memory_range_protected(phys_addr_t start, >>> +                         phys_addr_t end) >>> +{ >>> +    return rsi_set_memory_range(start, end, RSI_RIPAS_RAM, >>> +                    RSI_CHANGE_DESTROYED); >>> +} >>> + >>> +/* >>> + * Convert the specified range to RAM. Do not convert any pages that may have >>> + * been DESTROYED, without our permission. >>> + */ >>> +static inline int rsi_set_memory_range_protected_safe(phys_addr_t start, >>> +                              phys_addr_t end) >>> +{ >>> +    return rsi_set_memory_range(start, end, RSI_RIPAS_RAM, >>> +                    RSI_NO_CHANGE_DESTROYED); >>> +} >>> + >>> +static inline int rsi_set_memory_range_shared(phys_addr_t start, >>> +                          phys_addr_t end) >>> +{ >>> +    return rsi_set_memory_range(start, end, RSI_RIPAS_EMPTY, 0); >>> +} >>> +#endif >> >> s/0/RSI_NO_CHANGE_DESTROYED > > This is not required as we do not care if the GRANULE was destroyed or > not, since it is going to be "UNUSED" anyway in a protected way (RIPAS_EMPTY). And we do not rely on the contents of the memory being > preserved, when the page is made shared (In fact we cannot do that > with Arm CCA). > > Thus we do not get any security benefits with the flag. The flag is ONLY > useful, when the Realm does a "blanket" IPA_STATE_SET(RIPAS_RAM) for > all of its memory area described as RAM. In this case, we want to make > sure that the Host hasn't destroyed any DATA that was loaded (and > measured) in the "NEW" state. > > e.g, Host loads Kernel at Addr X in RAM (which is transitioned to RIPAS_RAM, measured in RIM by RMM) and ACTIVATEs the Realm. Host could then destroy some pages of the loaded image before the Realm boots (thus > transitioning into DESTROYED). But for the Realm, at early boot, it is > much easier to "mark" the entire RAM region as RIPAS_RAM, > > > for_each_memory_region(region) { >     set_ipa_state_range(region->start, region->end, RIPAS_RAM, RSI_NO_CHANGE_DESTROYED); > } > > rather than performing: > > for_each_granule(g in DRAM) : > > switch (rsi_get_ipa_state(g)) { > case RIPAS_EMPTY: rsi_set_ipa_state(g, RIPAS_RAM); break; > case RIPAS_RAM: break; /* Nothing to do */ > case DESTROYED: BUG(); > } > > The point was 0 and RSI_NO_CHANGE_DESTROYED are interchangeable. Since RSI_NO_CHANGE_DESTROYED has been defined as 0, why we don't used RSI_NO_CHANGE_DESTROYED? > >> s/#endif/#endif /* __ASM_RSI_H_ */ >> >>> diff --git a/arch/arm64/include/asm/rsi_cmds.h b/arch/arm64/include/asm/rsi_cmds.h >>> index 89e907f3af0c..acb557dd4b88 100644 >>> --- a/arch/arm64/include/asm/rsi_cmds.h >>> +++ b/arch/arm64/include/asm/rsi_cmds.h >>> @@ -10,6 +10,11 @@ >>>   #include >>> +enum ripas { >>> +    RSI_RIPAS_EMPTY, >>> +    RSI_RIPAS_RAM, >>> +}; >>> + >>>   static inline unsigned long rsi_request_version(unsigned long req, >>>                           unsigned long *out_lower, >>>                           unsigned long *out_higher) >>> @@ -35,4 +40,21 @@ static inline unsigned long rsi_get_realm_config(struct realm_config *cfg) >>>       return res.a0; >>>   } >>> +static inline unsigned long rsi_set_addr_range_state(phys_addr_t start, >>> +                             phys_addr_t end, >>> +                             enum ripas state, >>> +                             unsigned long flags, >>> +                             phys_addr_t *top) >>> +{ >>> +    struct arm_smccc_res res; >>> + >>> +    arm_smccc_smc(SMC_RSI_IPA_STATE_SET, start, end, state, >>> +              flags, 0, 0, 0, &res); >>> + >>> +    if (top) >>> +        *top = res.a1; >>> + >>> +    return res.a0; >>> +} >>> + >>>   #endif >>> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile >>> index 763824963ed1..a483b916ed11 100644 >>> --- a/arch/arm64/kernel/Makefile >>> +++ b/arch/arm64/kernel/Makefile >>> @@ -33,7 +33,8 @@ obj-y            := debug-monitors.o entry.o irq.o fpsimd.o        \ >>>                  return_address.o cpuinfo.o cpu_errata.o        \ >>>                  cpufeature.o alternative.o cacheinfo.o        \ >>>                  smp.o smp_spin_table.o topology.o smccc-call.o    \ >>> -               syscall.o proton-pack.o idle.o patching.o pi/ >>> +               syscall.o proton-pack.o idle.o patching.o pi/    \ >>> +               rsi.o >>>   obj-$(CONFIG_COMPAT)            += sys32.o signal32.o            \ >>>                          sys_compat.o >>> diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c >>> new file mode 100644 >>> index 000000000000..f01bff9dab04 >>> --- /dev/null >>> +++ b/arch/arm64/kernel/rsi.c >>> @@ -0,0 +1,77 @@ >>> +// SPDX-License-Identifier: GPL-2.0-only >>> +/* >>> + * Copyright (C) 2023 ARM Ltd. >>> + */ >>> + >>> +#include >>> +#include >>> +#include >>> +#include >>> + >>> +DEFINE_STATIC_KEY_FALSE_RO(rsi_present); >>> +EXPORT_SYMBOL(rsi_present); >>> + >>> +static bool rsi_version_matches(void) >>> +{ >>> +    unsigned long ver_lower, ver_higher; >>> +    unsigned long ret = rsi_request_version(RSI_ABI_VERSION, >>> +                        &ver_lower, >>> +                        &ver_higher); >>> + >>> +    if (ret == SMCCC_RET_NOT_SUPPORTED) >>> +        return false; >>> + >>> +    if (ret != RSI_SUCCESS) { >>> +        pr_err("RME: RMM doesn't support RSI version %u.%u. Supported range: %lu.%lu-%lu.%lu\n", >>> +               RSI_ABI_VERSION_MAJOR, RSI_ABI_VERSION_MINOR, >>> +               RSI_ABI_VERSION_GET_MAJOR(ver_lower), >>> +               RSI_ABI_VERSION_GET_MINOR(ver_lower), >>> +               RSI_ABI_VERSION_GET_MAJOR(ver_higher), >>> +               RSI_ABI_VERSION_GET_MINOR(ver_higher)); >>> +        return false; >>> +    } >>> + >>> +    pr_info("RME: Using RSI version %lu.%lu\n", >>> +        RSI_ABI_VERSION_GET_MAJOR(ver_lower), >>> +        RSI_ABI_VERSION_GET_MINOR(ver_lower)); >>> + >>> +    return true; >>> +} >>> + >>> +void __init arm64_rsi_setup_memory(void) >>> +{ >>> +    u64 i; >>> +    phys_addr_t start, end; >>> + >>> +    if (!is_realm_world()) >>> +        return; >>> + >>> +    /* >>> +     * Iterate over the available memory ranges and convert the state to >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >>                                               blocks and convert them to > > TBH, I don't see any significant difference between the two. Am I > missing something ? > for_each_mem_range() is a helper provided by memory block management module. So 'memory block' sounds like more accurate than broadly used term "memory range" here. >> >>> +     * protected memory. We should take extra care to ensure that we DO NOT >>> +     * permit any "DESTROYED" pages to be converted to "RAM". >>> +     * >>> +     * BUG_ON is used because if the attempt to switch the memory to >>> +     * protected has failed here, then future accesses to the memory are >>> +     * simply going to be reflected as a fault which we can't handle. >>> +     * Bailing out early prevents the guest limping on and dieing later. >>> +     */ >>> +    for_each_mem_range(i, &start, &end) { >>> +        BUG_ON(rsi_set_memory_range_protected_safe(start, end)); >>> +    } >>> +} >>> + >> >> If I'm understanding the code completely, this changes the memory state from >> RIPAS_EMPTY to RIPAS_RAM so that the following page faults can be routed to >> host properly. Otherwise, a SEA is injected to the realm according to >> tf-rmm/runtime/core/exit.c::handle_data_abort(). The comments can be more >> explicit to replace "fault" with "SEA (Synchronous External Abort)". > > Agreed.  SEA is more accurate than fault. > Ok. >> >> Besides, this forces a guest exit with reason RMI_EXIT_RIPAS_CHANGE which is >> handled by the host, where RMI_RTT_SET_RIPAS is triggered to convert the memory >> state from RIPAS_EMPTY to RIPAS_RAM. The question is why the conversion can't >> be done by VMM (QEMU)? > > A VMM could potentially do this via INIT_RIPAS at Realm creation for > the entire RAM. But, as far as the Realm is concerned it is always safer to do this step and is relatively a lightweight operation at boot. Physical pages need not be allocated/mapped in stage2 with the IPA State change. > Ok. Thanks for the explanation. > > Suzuki >> >>> +void __init arm64_rsi_init(void) >>> +{ >>> +    /* >>> +     * If PSCI isn't using SMC, RMM isn't present. Don't try to execute an >>> +     * SMC as it could be UNDEFINED. >>> +     */ >>> +    if (!psci_early_test_conduit(SMCCC_CONDUIT_SMC)) >>> +        return; >>> +    if (!rsi_version_matches()) >>> +        return; >>> + >>> +    static_branch_enable(&rsi_present); >>> +} >>> + >>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c >>> index a096e2451044..143f87615af0 100644 >>> --- a/arch/arm64/kernel/setup.c >>> +++ b/arch/arm64/kernel/setup.c >>> @@ -43,6 +43,7 @@ >>>   #include >>>   #include >>>   #include >>> +#include >>>   #include >>>   #include >>>   #include >>> @@ -293,6 +294,11 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p) >>>        * cpufeature code and early parameters. >>>        */ >>>       jump_label_init(); >>> +    /* >>> +     * Init RSI before early param so that "earlycon" console uses the >>> +     * shared alias when in a realm >>> +     */ >>> +    arm64_rsi_init(); >>>       parse_early_param(); >>>       dynamic_scs_init(); >>> @@ -328,6 +334,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p) >>>       arm64_memblock_init(); >>> +    arm64_rsi_setup_memory(); >>> + >>>       paging_init(); >>>       acpi_table_upgrade(); >> Thanks, Gavin