On Mon, Oct 12, 2015 at 01:16:49PM +0100, Daniel P. Berrange wrote:
> This looks for existance of DMAR (Intel) and IVRS (AMD)
> files under /sys/firmware/acpi/tables/, as a sign that
> the platform has IOMMU present & enabled in the BIOS.
>
> If these are present and /sys/kernel/iommu_groups does
> not contain any entries this is taken as a sign that
> the kernel has not enabled the IOMMU currently.
>
> If no ACPI tables are found we can't distinguish between
> disabled in BIOS and not present in the hardware, so we
> have to give the user a generic hint.
>
> Signed-off-by: Daniel P. Berrange <berrange@xxxxxxxxxx>
> ---
>
> Changed in v2:
>
> - Completely refactor the check to remove false
> positives and cope with iommu being enabled
> by default
> - Add AMD support
>
> tools/virt-host-validate-common.c | 64 +++++++++++++++++++++++++++++++++++++++
> tools/virt-host-validate-common.h | 3 ++
> tools/virt-host-validate-qemu.c | 6 ++++
> 3 files changed, 73 insertions(+)
>
> diff --git a/tools/virt-host-validate-common.c b/tools/virt-host-validate-common.c
> index a88fc56..38128b1 100644
> --- a/tools/virt-host-validate-common.c
> +++ b/tools/virt-host-validate-common.c
> @@ -26,6 +26,7 @@
> #include <stdio.h>
> #include <unistd.h>
> #include <sys/utsname.h>
> +#include <sys/stat.h>
> #include <mntent.h>
>
> #include "virutil.h"
> @@ -341,3 +342,66 @@ int virHostValidateCGroupController(const char *hvname,
> return -1;
> return 0;
> }
> +
> +int virHostValidateIOMMU(const char *hvname,
> + virHostValidateLevel level)
> +{
> + struct stat sb;
> + const char *bootarg = NULL;
> + bool isAMD = false, isIntel = false;
> +
> + if (virHostValidateHasCPUFlag("vmx"))
> + isIntel = true;
> + else if (virHostValidateHasCPUFlag("svm"))
> + isAMD = true;
> + else
> + /* XXX PPC/ARM/etc support */
> + return 0;
> +
> + virHostMsgCheck(hvname, "%s", _("for device assignment IOMMU support"));
> +
> + if (isIntel) {
> + if (access("/sys/firmware/acpi/tables/DMAR", F_OK) == 0) {
> + virHostMsgPass();
> + bootarg = "intel_iommu=on";
> + } else {
> + virHostMsgFail(level,
> + "No ACPI DMAR table found, IOMMU either "
> + "disabled in BIOS or not supported by this "
> + "hardware platform");
> + return -1;
> + }
> + } else if (isAMD) {
> + if (access("/sys/firmware/acpi/tables/IVRS", F_OK) == 0) {
> + virHostMsgPass();
> + bootarg = "iommu=pt iommu=1";
> + } else {
> + virHostMsgFail(level,
> + "No ACPI IVRS table found, IOMMU either "
> + "disabled in BIOS or not supported by this "
> + "hardware platform");
> + return -1;
> + }
> + } else {
> + virHostMsgFail(level,
> + "Unknown if this platform has IOMMU support");
> + return -1;
> + }
> +
> +
> + /* We can only check on newer kernels with iommu groups & vfio */
> + if (stat("/sys/kernel/iommu_groups", &sb) < 0)
> + return 0;
> +
> + if (!S_ISDIR(sb.st_mode))
> + return 0;
> +
> + virHostMsgCheck(hvname, "%s", _("if IOMMU is enabled by kernel"));
> + if (sb.st_nlink <= 2) {
> + virHostMsgFail(level,
> + "IOMMU appears to be disabled in kernel. "
> + "Add %s to kernel cmdline arguments", bootarg);
> + return -1;
> + }
Opps, Laine pointed out on IRC I should have
virHostMsgPass();
called here on success
> + return 0;
> +}
Regards,
Daniel
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