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([2a01:e0a:59e:9d80:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id y20-20020ad445b4000000b006816ffc7113sm5210233qvu.63.2024.01.25.00.18.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 25 Jan 2024 00:18:06 -0800 (PST) Message-ID: <8d85ff1d-fed9-49c9-9fe3-b401e0921533@redhat.com> Date: Thu, 25 Jan 2024 09:18:02 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] target/i386/host-cpu: Use iommu phys_bits with VFIO assigned devices on Intel h/w Content-Language: en-US To: Vivek Kasireddy , qemu-devel@nongnu.org Cc: Gerd Hoffmann , =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , Alex Williamson , =?UTF-8?Q?C=C3=A9dric_Le_Goater?= , Laszlo Ersek , Dongwon Kim , Yanghang Liu References: <20240118192049.1796763-1-vivek.kasireddy@intel.com> From: Eric Auger In-Reply-To: <20240118192049.1796763-1-vivek.kasireddy@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=eauger@redhat.com; helo=us-smtp-delivery-124.mimecast.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, DKIMWL_WL_HIGH=-1.5, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SORBS_WEB=1.5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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 Vivek, On 1/18/24 20:20, Vivek Kasireddy wrote: > Recent updates in OVMF and Seabios have resulted in MMIO regions > being placed at the upper end of the physical address space. As a > result, when a Host device is assigned to the Guest via VFIO, the > following mapping failures occur when VFIO tries to map the MMIO > regions of the device: > VFIO_MAP_DMA failed: Invalid argument > vfio_dma_map(0x557b2f2736d0, 0x380000000000, 0x1000000, 0x7f98ac400000) = -22 (Invalid argument) > > The above failures are mainly seen on some Intel platforms where > the physical address width is larger than the Host's IOMMU > address width. In these cases, VFIO fails to map the MMIO regions > because the IOVAs would be larger than the IOMMU aperture regions. > > Therefore, one way to solve this problem would be to ensure that > cpu->phys_bits = > This can be done by parsing the IOMMU caps value from sysfs and > extracting the address width and using it to override the > phys_bits value as shown in this patch. > > Previous attempt at solving this issue in OVMF: > https://edk2.groups.io/g/devel/topic/102359124 > > Cc: Gerd Hoffmann > Cc: Philippe Mathieu-Daudé > Cc: Alex Williamson > Cc: Cédric Le Goater > Cc: Laszlo Ersek > Cc: Dongwon Kim > Acked-by: Gerd Hoffmann > Tested-by: Yanghang Liu > Signed-off-by: Vivek Kasireddy > > --- > v2: > - Replace the term passthrough with assigned (Laszlo) > - Update the commit message to note that both OVMF and Seabios > guests are affected (Cédric) > - Update the subject to indicate what is done in the patch > --- > target/i386/host-cpu.c | 61 +++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 60 insertions(+), 1 deletion(-) > > diff --git a/target/i386/host-cpu.c b/target/i386/host-cpu.c > index 92ecb7254b..5c9fcd7dc2 100644 > --- a/target/i386/host-cpu.c > +++ b/target/i386/host-cpu.c > @@ -12,6 +12,8 @@ > #include "host-cpu.h" > #include "qapi/error.h" > #include "qemu/error-report.h" > +#include "qemu/config-file.h" > +#include "qemu/option.h" > #include "sysemu/sysemu.h" > > /* Note: Only safe for use on x86(-64) hosts */ > @@ -51,11 +53,58 @@ static void host_cpu_enable_cpu_pm(X86CPU *cpu) > env->features[FEAT_1_ECX] |= CPUID_EXT_MONITOR; > } > > +static int intel_iommu_check(void *opaque, QemuOpts *opts, Error **errp) > +{ > + g_autofree char *dev_path = NULL, *iommu_path = NULL, *caps = NULL; > + const char *driver = qemu_opt_get(opts, "driver"); > + const char *device = qemu_opt_get(opts, "host"); > + uint32_t *iommu_phys_bits = opaque; > + struct stat st; > + uint64_t iommu_caps; > + > + /* > + * Check if the user requested VFIO device assignment. We don't have > + * to limit phys_bits if there are no valid assigned devices. > + */ > + if (g_strcmp0(driver, "vfio-pci") || !device) { > + return 0; > + } > + > + dev_path = g_strdup_printf("/sys/bus/pci/devices/%s", device); > + if (stat(dev_path, &st) < 0) { > + return 0; > + } > + > + iommu_path = g_strdup_printf("%s/iommu/intel-iommu/cap", dev_path); > + if (stat(iommu_path, &st) < 0) { > + return 0; > + } > + > + if (g_file_get_contents(iommu_path, &caps, NULL, NULL)) { > + if (sscanf(caps, "%lx", &iommu_caps) != 1) { > + return 0; > + } > + *iommu_phys_bits = ((iommu_caps >> 16) & 0x3f) + 1; > + } > + > + return 0; > +} > + > +static uint32_t host_iommu_phys_bits(void) > +{ > + uint32_t iommu_phys_bits = 0; > + > + qemu_opts_foreach(qemu_find_opts("device"), > + intel_iommu_check, &iommu_phys_bits, NULL); > + return iommu_phys_bits; > +} > + > static uint32_t host_cpu_adjust_phys_bits(X86CPU *cpu) > { > uint32_t host_phys_bits = host_cpu_phys_bits(); > + uint32_t iommu_phys_bits = host_iommu_phys_bits(); > uint32_t phys_bits = cpu->phys_bits; > - static bool warned; > + static bool warned, warned2; > > /* > * Print a warning if the user set it to a value that's not the > @@ -78,6 +127,16 @@ static uint32_t host_cpu_adjust_phys_bits(X86CPU *cpu) > } > } > > + if (iommu_phys_bits && phys_bits > iommu_phys_bits) { > + phys_bits = iommu_phys_bits; are you allowed to change the host cpu characteristics without taking care of compats for migration? I don't know anything about OVMF but why isn't the "cap" not directly read in the FW stack? Thanks Eric > + if (!warned2) { > + warn_report("Using physical bits (%u)" > + " to prevent VFIO mapping failures", > + iommu_phys_bits); > + warned2 = true; > + } > + } > + > return phys_bits; > } >