Implement ioctl command VFIO_CHECK_EXTENSION.

PiperOrigin-RevId: 615540633

pkg/abi/linux/vfio.go

@@ -20,9 +20,15 @@ package linux
 const (
 	VFIO_TYPE = ';'
 	VFIO_BASE = 100
+
+	// VFIO extensions.
+	VFIO_TYPE1_IOMMU     = 1
+	VFIO_SPAPR_TCE_IOMMU = 2
+	VFIO_TYPE1v2_IOMMU   = 3
 )
 
 // IOCTLs for VFIO file descriptor from include/uapi/linux/vfio.h.
 var (
+	VFIO_CHECK_EXTENSION     = IO(VFIO_TYPE, VFIO_BASE+1)
 	VFIO_GROUP_SET_CONTAINER = IO(VFIO_TYPE, VFIO_BASE+4)
 )

pkg/sentry/devices/tpuproxy/seccomp_filter.go

@@ -57,6 +57,10 @@ func Filters() seccomp.SyscallRules {
 				seccomp.NonNegativeFD{},
 				seccomp.EqualTo(linux.VFIO_GROUP_SET_CONTAINER),
 			},
+			seccomp.PerArg{
+				seccomp.NonNegativeFD{},
+				seccomp.EqualTo(linux.VFIO_CHECK_EXTENSION),
+			},
 		},
 	})
 }

pkg/sentry/devices/tpuproxy/vfio.go

@@ -18,10 +18,13 @@ import (
 	"fmt"
 
 	"golang.org/x/sys/unix"
+	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/errors/linuxerr"
 	"gvisor.dev/gvisor/pkg/fdnotifier"
+	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
+	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
 	"gvisor.dev/gvisor/pkg/usermem"
 	"gvisor.dev/gvisor/pkg/waiter"
@@ -77,5 +80,45 @@ func (fd *vfioFd) Epollable() bool {
 
 // Ioctl implements vfs.FileDescriptionImpl.Ioctl.
 func (fd *vfioFd) Ioctl(ctx context.Context, uio usermem.IO, sysno uintptr, args arch.SyscallArguments) (uintptr, error) {
+	cmd := args[1].Uint()
+	t := kernel.TaskFromContext(ctx)
+	if t == nil {
+		panic("Ioctl should be called from a task context")
+	}
+	switch cmd {
+	case linux.VFIO_CHECK_EXTENSION:
+		return fd.checkExtension(extension(args[2].Int()))
+	}
 	return 0, linuxerr.ENOSYS
 }
+
+// checkExtension returns a positive integer when the given VFIO extension
+// is supported, otherwise, it returns 0.
+func (fd *vfioFd) checkExtension(ext extension) (uintptr, error) {
+	switch ext {
+	case linux.VFIO_TYPE1_IOMMU, linux.VFIO_SPAPR_TCE_IOMMU, linux.VFIO_TYPE1v2_IOMMU:
+		ret, err := ioctlInvoke[int32](fd.hostFd, linux.VFIO_CHECK_EXTENSION, int32(ext))
+		if err != nil {
+			log.Warningf("check VFIO extension %s: %v", ext, err)
+			return 0, err
+		}
+		return ret, nil
+	}
+	return 0, linuxerr.EINVAL
+}
+
+// VFIO extension.
+type extension int32
+
+// String implements fmt.Stringer for VFIO extension string representation.
+func (e extension) String() string {
+	switch e {
+	case linux.VFIO_TYPE1_IOMMU:
+		return "VFIO_TYPE1_IOMMU"
+	case linux.VFIO_SPAPR_TCE_IOMMU:
+		return "VFIO_SPAPR_TCE_IOMMU"
+	case linux.VFIO_TYPE1v2_IOMMU:
+		return "VFIO_TYPE1v2_IOMMU"
+	}
+	return ""
+}