[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 3/4] amd-iommu: disable iommu_hap_pt_share with AMD IOMMUs
Roger,I am not quite sure why you would disable "iommu_hap_pt_share" for AMD IOMMU. The current implementation assumes that the p2m can be shared. Also, I feel that simply just set iommu_hap_pt_share = 0 (while still having several places in the AMD iommu drivers and p2m-pt.c assuming that it can be shared) seems a bit messy. Thanks, Suravee On 06/04/2014 05:06 AM, Roger Pau Monne wrote: This message has been archived. View the original item <http://ausev2.amd.com/EnterpriseVault/ViewMessage.asp?VaultId=1EBD12133601C6E47868220A36CFE2B201110000amdvault.amd.com&SavesetId=201407064668470~201406041006380000~Z~B0E2C95E06CD0962996EB51CFC709411> According to the comment in p2m.h, AMD IOMMUs don't work correctly with page types different than p2m_ram_rw when the p2m is shared between HAP and IOMMU, so disable this sharing when using AMD IOMMUs. Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> Cc: Xiantao Zhang <xiantao.zhang@xxxxxxxxx> Cc: Jan Beulich <jbeulich@xxxxxxxx> --- I have not tested this patch on AMD hardware, so I would like some confirmation that this actually works. --- Changes since v1: - Add a debug message when disabling iommu_hap_pt_share. --- xen/drivers/passthrough/amd/iommu_init.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/xen/drivers/passthrough/amd/iommu_init.c b/xen/drivers/passthrough/amd/iommu_init.c index b2f74ef..56bda00 100644 --- a/xen/drivers/passthrough/amd/iommu_init.c +++ b/xen/drivers/passthrough/amd/iommu_init.c @@ -1255,6 +1255,14 @@ int __init amd_iommu_init(void) if ( iterate_ivrs_mappings(amd_iommu_setup_device_table) != 0 ) goto error_out; + /* + * Disable sharing HAP page tables with AMD IOMMU, + * since it only supports p2m_ram_rw, and this would + * prevent doing IO to/from mapped grant frames. + */ + iommu_hap_pt_share = 0; + printk(XENLOG_DEBUG "AMD-Vi: Disabled HAP memory map sharing with IOMMU"); + /* per iommu initialization */ for_each_amd_iommu ( iommu ) if ( amd_iommu_init_one(iommu) != 0 ) -- 1.7.7.5 (Apple Git-26) _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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