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[88.187.86.199]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38dd4d826c6sm6963579f8f.69.2025.02.10.06.40.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 10 Feb 2025 06:40:14 -0800 (PST) Message-ID: <0a148b5c-23e9-4c4b-84fc-70f04d5adf29@linaro.org> Date: Mon, 10 Feb 2025 15:40:13 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 7/9] cpu: Introduce cpu_get_phys_bits() To: =?UTF-8?Q?C=C3=A9dric_Le_Goater?= , qemu-devel@nongnu.org Cc: Alex Williamson , Richard Henderson , Paolo Bonzini , Eduardo Habkost , Marcel Apfelbaum , Yanan Wang , Zhao Liu References: <20250130134346.1754143-1-clg@redhat.com> <20250130134346.1754143-8-clg@redhat.com> Content-Language: en-US From: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= In-Reply-To: <20250130134346.1754143-8-clg@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::432; envelope-from=philmd@linaro.org; helo=mail-wr1-x432.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi Cédric, On 30/1/25 14:43, Cédric Le Goater wrote: > The Intel CPU has a complex history regarding setting of the physical > address space width on KVM. A 'phys_bits' field and a "phys-bits" > property were added by commit af45907a1328 ("target-i386: Allow > physical address bits to be set") to tune this value. > > In certain circumstances, it is interesting to know this value to > check that all the conditions are met for optimal operation. For > instance, when the system has a 39-bit IOMMU address space width and a > larger CPU physical address space, we expect issues when mapping the > MMIO regions of passthrough devices and it would good to report to the > user. These hybrid HW configs can be found on some consumer grade > processors or when using a vIOMMU device with default settings. > > For this purpose, add an helper routine and a CPUClass callback to > return the physical address space width of a CPU. > > Cc: Richard Henderson > Cc: Paolo Bonzini > Cc: Eduardo Habkost > Cc: Marcel Apfelbaum > Cc: "Philippe Mathieu-Daudé" > Cc: Yanan Wang > Cc: Zhao Liu > Signed-off-by: Cédric Le Goater > --- > include/hw/core/cpu.h | 9 +++++++++ > include/hw/core/sysemu-cpu-ops.h | 6 ++++++ > cpu-target.c | 5 +++++ > hw/core/cpu-system.c | 11 +++++++++++ > target/i386/cpu.c | 6 ++++++ > 5 files changed, 37 insertions(+) > > diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h > index fb397cdfc53d12d40d3e4e7f86251fc31c48b9f6..1b3eead102ce62fcee55ab0ed5e0dff327fa2fc5 100644 > --- a/include/hw/core/cpu.h > +++ b/include/hw/core/cpu.h > @@ -748,6 +748,14 @@ int cpu_asidx_from_attrs(CPUState *cpu, MemTxAttrs attrs); > */ > bool cpu_virtio_is_big_endian(CPUState *cpu); > > +/** > + * cpu_get_phys_bits: > + * @cpu: CPU > + * > + * Return the physical address space width of the CPU @cpu. > + */ > +uint32_t cpu_get_phys_bits(const CPUState *cpu); > + > #endif /* CONFIG_USER_ONLY */ > > /** > @@ -1168,6 +1176,7 @@ void cpu_exec_unrealizefn(CPUState *cpu); > void cpu_exec_reset_hold(CPUState *cpu); > > const char *target_name(void); > +uint32_t target_phys_bits(void); > > #ifdef COMPILING_PER_TARGET > > diff --git a/include/hw/core/sysemu-cpu-ops.h b/include/hw/core/sysemu-cpu-ops.h > index 0df5b058f50073e47d2a6b8286be5204776520d2..210b3ed57985525795b81559e41e0085969210d5 100644 > --- a/include/hw/core/sysemu-cpu-ops.h > +++ b/include/hw/core/sysemu-cpu-ops.h > @@ -81,6 +81,12 @@ typedef struct SysemuCPUOps { > */ > bool (*virtio_is_big_endian)(CPUState *cpu); > > + /** > + * @get_phys_bits: Callback to return the physical address space > + * width of a CPU. > + */ > + uint32_t (*get_phys_bits)(const CPUState *cpu); Using 32-bit isn't really relevant IMHO, I'd return an unsigned type. > + > /** > * @legacy_vmsd: Legacy state for migration. > * Do not use in new targets, use #DeviceClass::vmsd instead. > diff --git a/cpu-target.c b/cpu-target.c > index 667688332c929aa53782c94343def34571272d5f..88158272c06cc42424d435b9701e33735f080239 100644 > --- a/cpu-target.c > +++ b/cpu-target.c > @@ -472,3 +472,8 @@ const char *target_name(void) > { > return TARGET_NAME; > } > + > +uint32_t target_phys_bits(void) > +{ > + return TARGET_PHYS_ADDR_SPACE_BITS; > +} > diff --git a/hw/core/cpu-system.c b/hw/core/cpu-system.c > index 6aae28a349a7a377d010ff9dcab5ebc29e1126ca..05067d84f4258facf4252216f17729e390d38eae 100644 > --- a/hw/core/cpu-system.c > +++ b/hw/core/cpu-system.c > @@ -60,6 +60,17 @@ hwaddr cpu_get_phys_page_attrs_debug(CPUState *cpu, vaddr addr, > return cc->sysemu_ops->get_phys_page_debug(cpu, addr); > } > > +uint32_t cpu_get_phys_bits(const CPUState *cpu) > +{ > + CPUClass *cc = CPU_GET_CLASS(cpu); > + > + if (cc->sysemu_ops->get_phys_bits) { > + return cc->sysemu_ops->get_phys_bits(cpu); > + } > + > + return target_phys_bits(); With heterogeneous emulation in mind, I'd rather this to be a mandatory CPUClass handler. > +} > + > hwaddr cpu_get_phys_page_debug(CPUState *cpu, vaddr addr) > { > MemTxAttrs attrs = {}; > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index b5dd60d2812e0c3d13c1743fd485a9068ab29c4f..01cf9a44963710a415c755c17582730f75233143 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -8393,6 +8393,11 @@ static bool x86_cpu_get_paging_enabled(const CPUState *cs) > > return cpu->env.cr[0] & CR0_PG_MASK; > } > + > +static uint32_t x86_cpu_get_phys_bits(const CPUState *cs) > +{ > + return X86_CPU(cs)->phys_bits; > +} > #endif /* !CONFIG_USER_ONLY */ > > static void x86_cpu_set_pc(CPUState *cs, vaddr value) > @@ -8701,6 +8706,7 @@ static const struct SysemuCPUOps i386_sysemu_ops = { > .get_memory_mapping = x86_cpu_get_memory_mapping, > .get_paging_enabled = x86_cpu_get_paging_enabled, > .get_phys_page_attrs_debug = x86_cpu_get_phys_page_attrs_debug, > + .get_phys_bits = x86_cpu_get_phys_bits, > .asidx_from_attrs = x86_asidx_from_attrs, > .get_crash_info = x86_cpu_get_crash_info, > .write_elf32_note = x86_cpu_write_elf32_note,