After applying this patch, the Q35 + OVMF L2 VM with a igbvf will not throw the error like: [1]VFIO_MAP_DMA failed: Invalid argument. [2]vfio_dma_map(0x560a1a64e3b0, 0x383000004000, 0x4000, 0x7fcfc4053000) = -22 (Invalid argument)
Tested-by: Yanghang Liu <yangh...@redhat.com> On Wed, Dec 6, 2023 at 2:08 AM Cédric Le Goater <clego...@redhat.com> wrote: > > On 11/13/23 08:32, Vivek Kasireddy wrote: > > A recent OVMF update has resulted in MMIO regions being placed at > > the upper end of the physical address space. As a result, when a > > Host device is passthrough'd 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) > > OVMF and Seabios guests are impacted. Seabios 1.16.3 introduced > the same change of the pci window placement. > > C. > > > 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 = <IOMMU 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 <kra...@redhat.com> > > Cc: Philippe Mathieu-Daudé <phi...@linaro.org> > > Cc: Alex Williamson <alex.william...@redhat.com> > > Cc: Laszlo Ersek <ler...@redhat.com> > > Cc: Dongwon Kim <dongwon....@intel.com> > > Signed-off-by: Vivek Kasireddy <vivek.kasire...@intel.com> > > --- > > 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..8326ec95bc 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 is passthroughing any devices via VFIO. We don't > > + * have to limit phys_bits if there are no valid passthrough 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; > > + if (!warned2) { > > + warn_report("Using physical bits (%u)" > > + " to prevent VFIO mapping failures", > > + iommu_phys_bits); > > + warned2 = true; > > + } > > + } > > + > > return phys_bits; > > } > > > >
