Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757059AbdCTS1p (ORCPT ); Mon, 20 Mar 2017 14:27:45 -0400 Received: from foss.arm.com ([217.140.101.70]:44096 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756787AbdCTS1O (ORCPT ); Mon, 20 Mar 2017 14:27:14 -0400 From: Suzuki K Poulose To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, christoffer.dall@linaro.org, marc.zyngier@arm.com, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Suzuki K Poulose Subject: [PATCH] kvm: arm/arm64: Rework gpa callback handlers Date: Mon, 20 Mar 2017 18:26:42 +0000 Message-Id: <1490034402-28850-1-git-send-email-suzuki.poulose@arm.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4026 Lines: 115 In order to perform an operation on a gpa range, the hyp iterates over each page in a user memory slot for the given range. This is inefficient while dealing with a big range (e.g, a VMA), especially while unmaping a range. At present, with stage2 unmap on a range with a hugepage backed region, we clear the PMD when we unmap the first page in the loop. The remaining iterations simply traverse the page table down to the PMD level only to see that nothing is in there. This patch reworks the code to invoke the callback handlers on the biggest range possible within the memory slot to avoid reduce the number of iterations. Cc: Marc Zyngier Cc: Christoffer Dall Signed-off-by: Suzuki K Poulose --- arch/arm/kvm/mmu.c | 31 +++++++++++++------------------ 1 file changed, 13 insertions(+), 18 deletions(-) diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index 37e67f5..8357fed 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -1524,7 +1524,8 @@ static int handle_hva_to_gpa(struct kvm *kvm, unsigned long start, unsigned long end, int (*handler)(struct kvm *kvm, - gpa_t gpa, void *data), + gpa_t gpa, u64 size, + void *data), void *data) { struct kvm_memslots *slots; @@ -1536,7 +1537,7 @@ static int handle_hva_to_gpa(struct kvm *kvm, /* we only care about the pages that the guest sees */ kvm_for_each_memslot(memslot, slots) { unsigned long hva_start, hva_end; - gfn_t gfn, gfn_end; + gfn_t gpa; hva_start = max(start, memslot->userspace_addr); hva_end = min(end, memslot->userspace_addr + @@ -1544,25 +1545,16 @@ static int handle_hva_to_gpa(struct kvm *kvm, if (hva_start >= hva_end) continue; - /* - * {gfn(page) | page intersects with [hva_start, hva_end)} = - * {gfn_start, gfn_start+1, ..., gfn_end-1}. - */ - gfn = hva_to_gfn_memslot(hva_start, memslot); - gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot); - - for (; gfn < gfn_end; ++gfn) { - gpa_t gpa = gfn << PAGE_SHIFT; - ret |= handler(kvm, gpa, data); - } + gpa = hva_to_gfn_memslot(hva_start, memslot) << PAGE_SHIFT; + ret |= handler(kvm, gpa, (u64)(hva_end - hva_start), data); } return ret; } -static int kvm_unmap_hva_handler(struct kvm *kvm, gpa_t gpa, void *data) +static int kvm_unmap_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data) { - unmap_stage2_range(kvm, gpa, PAGE_SIZE); + unmap_stage2_range(kvm, gpa, size); return 0; } @@ -1589,10 +1581,11 @@ int kvm_unmap_hva_range(struct kvm *kvm, return 0; } -static int kvm_set_spte_handler(struct kvm *kvm, gpa_t gpa, void *data) +static int kvm_set_spte_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data) { pte_t *pte = (pte_t *)data; + WARN_ON(size != PAGE_SIZE); /* * We can always call stage2_set_pte with KVM_S2PTE_FLAG_LOGGING_ACTIVE * flag clear because MMU notifiers will have unmapped a huge PMD before @@ -1618,11 +1611,12 @@ void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte) handle_hva_to_gpa(kvm, hva, end, &kvm_set_spte_handler, &stage2_pte); } -static int kvm_age_hva_handler(struct kvm *kvm, gpa_t gpa, void *data) +static int kvm_age_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data) { pmd_t *pmd; pte_t *pte; + WARN_ON(size != PAGE_SIZE && size != PMD_SIZE); pmd = stage2_get_pmd(kvm, NULL, gpa); if (!pmd || pmd_none(*pmd)) /* Nothing there */ return 0; @@ -1637,11 +1631,12 @@ static int kvm_age_hva_handler(struct kvm *kvm, gpa_t gpa, void *data) return stage2_ptep_test_and_clear_young(pte); } -static int kvm_test_age_hva_handler(struct kvm *kvm, gpa_t gpa, void *data) +static int kvm_test_age_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data) { pmd_t *pmd; pte_t *pte; + WARN_ON(size != PAGE_SIZE && size != PMD_SIZE); pmd = stage2_get_pmd(kvm, NULL, gpa); if (!pmd || pmd_none(*pmd)) /* Nothing there */ return 0; -- 2.7.4