6.14-stable review patch. If anyone has any objections, please let me know.
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From: Amit Machhiwal amachhiw@linux.ibm.com
commit b4392813bbc3b05fc01a33c64d8b8c6c62c32cfa upstream.
Currently on book3s-hv, the capability KVM_CAP_SPAPR_TCE_VFIO is only available for KVM Guests running on PowerNV and not for the KVM guests running on pSeries hypervisors. This prevents a pSeries L2 guest from leveraging the in-kernel acceleration for H_PUT_TCE_INDIRECT and H_STUFF_TCE hcalls that results in slow startup times for large memory guests.
Support for VFIO on pSeries was restored in commit f431a8cde7f1 ("powerpc/iommu: Reimplement the iommu_table_group_ops for pSeries"), making it possible to re-enable this capability on pSeries hosts.
This change enables KVM_CAP_SPAPR_TCE_VFIO for nested PAPR guests on pSeries, while maintaining the existing behavior on PowerNV. Booting an L2 guest with 128GB of memory shows an average 11% improvement in startup time.
Fixes: f431a8cde7f1 ("powerpc/iommu: Reimplement the iommu_table_group_ops for pSeries") Cc: stable@vger.kernel.org Reviewed-by: Vaibhav Jain vaibhav@linux.ibm.com Reviewed-by: Ritesh Harjani (IBM) ritesh.list@gmail.com Signed-off-by: Amit Machhiwal amachhiw@linux.ibm.com Signed-off-by: Madhavan Srinivasan maddy@linux.ibm.com Link: https://patch.msgid.link/20250220070002.1478849-1-amachhiw@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/kvm/powerpc.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
--- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -550,12 +550,9 @@ int kvm_vm_ioctl_check_extension(struct
#ifdef CONFIG_PPC_BOOK3S_64 case KVM_CAP_SPAPR_TCE: + fallthrough; case KVM_CAP_SPAPR_TCE_64: - r = 1; - break; case KVM_CAP_SPAPR_TCE_VFIO: - r = !!cpu_has_feature(CPU_FTR_HVMODE); - break; case KVM_CAP_PPC_RTAS: case KVM_CAP_PPC_FIXUP_HCALL: case KVM_CAP_PPC_ENABLE_HCALL: