From 572abd563befd56bee918316c4f7ab144d2decf5 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Tue, 29 Sep 2015 17:15:45 +1000 Subject: [PATCH] KVM: PPC: Book3S HV: Don't fall back to smaller HPT size in allocation ioctl Currently the KVM_PPC_ALLOCATE_HTAB will try to allocate the requested size of HPT, and if that is not possible, then try to allocate smaller sizes (by factors of 2) until either a minimum is reached or the allocation succeeds. This is not ideal for userspace, particularly in migration scenarios, where the destination VM really does require the size requested. Also, the minimum HPT size of 256kB may be insufficient for the guest to run successfully. This removes the fallback to smaller sizes on allocation failure for the KVM_PPC_ALLOCATE_HTAB ioctl. The fallback still exists for the case where the HPT is allocated at the time the first VCPU is run, if no HPT has been allocated by ioctl by that time. Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_64_mmu_hv.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 1f9c0a17f445..10722b1e38b5 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -70,7 +70,8 @@ long kvmppc_alloc_hpt(struct kvm *kvm, u32 *htab_orderp) } /* Lastly try successively smaller sizes from the page allocator */ - while (!hpt && order > PPC_MIN_HPT_ORDER) { + /* Only do this if userspace didn't specify a size via ioctl */ + while (!hpt && order > PPC_MIN_HPT_ORDER && !htab_orderp) { hpt = __get_free_pages(GFP_KERNEL|__GFP_ZERO|__GFP_REPEAT| __GFP_NOWARN, order - PAGE_SHIFT); if (!hpt) -- 2.20.1