Re: [PATCH v9 05/14] KVM: Allow range-based TLB invalidation from common code
From: Sean Christopherson <seanjc@google.com>
Date: 2023-08-15 22:30:52
Also in:
kvm, kvm-riscv, kvmarm, linux-mips, linux-riscv, lkml
On Fri, Aug 11, 2023, Raghavendra Rao Ananta wrote:
quoted hunk ↗ jump to hunk
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index ec169f5c7dce2..00f7bda9202f2 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c@@ -278,16 +278,14 @@ static inline bool kvm_available_flush_remote_tlbs_range(void) return kvm_x86_ops.flush_remote_tlbs_range; } -void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn, - gfn_t nr_pages) +int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm, gfn_t gfn, u64 nr_pages) { int ret = -EOPNOTSUPP; if (kvm_x86_ops.flush_remote_tlbs_range) - ret = static_call(kvm_x86_flush_remote_tlbs_range)(kvm, start_gfn, - nr_pages); - if (ret) - kvm_flush_remote_tlbs(kvm); + ret = static_call(kvm_x86_flush_remote_tlbs_range)(kvm, gfn, nr_pages); + + return ret;
Please write this as if (kvm_x86_ops.flush_remote_tlbs_range) return static_call(kvm_x86_flush_remote_tlbs_range)(kvm, gfn, nr_pages); return -EOPNOTSUPP; or alternatively if (!kvm_x86_ops.flush_remote_tlbs_range) return -EOPNOTSUPP; return static_call(kvm_x86_flush_remote_tlbs_range)(kvm, gfn, nr_pages); Hmm, I'll throw my official vote for the second version. The local "ret" is unnecessary and is suprisingly dangerous. I screwed up the conflict resolution when cherry-picking my CONFIG_HYPERV change to see what the conflict looked like and ended up with a double flush: int ret = -EOPNOTSUPP; if (kvm_x86_ops.flush_remote_tlbs_range) ret = static_call(kvm_x86_flush_remote_tlbs_range)(kvm, gfn, nr_pages); if (ret) kvm_flush_remote_tlbs(kvm); return ret; Dropping "ret" makes it much harder to get trigger happy when resolving conflicts. No need for a new version to fix the above, assuming Marc/Oliver is ok doing fixup when applying. Nit aside, looks good for x86, and I know of no conflicts, so take 'er away! Acked-by: Sean Christopherson <seanjc@google.com> _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel