From: Alexey Kardashevskiy <aik@ozlabs.ru> To: linuxppc-dev@lists.ozlabs.org Cc: Alexey Kardashevskiy <aik@ozlabs.ru>, Alex Williamson <alex.williamson@redhat.com>, David Gibson <david@gibson.dropbear.id.au>, Paul Mackerras <paulus@samba.org>, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org Subject: [PATCH kernel v10 08/10] KVM: PPC: Use preregistered memory API to access TCE list Date: Fri, 17 Mar 2017 16:09:57 +1100 [thread overview] Message-ID: <20170317050959.37312-9-aik@ozlabs.ru> (raw) In-Reply-To: <20170317050959.37312-1-aik@ozlabs.ru> VFIO on sPAPR already implements guest memory pre-registration when the entire guest RAM gets pinned. This can be used to translate the physical address of a guest page containing the TCE list from H_PUT_TCE_INDIRECT. This makes use of the pre-registrered memory API to access TCE list pages in order to avoid unnecessary locking on the KVM memory reverse map as we know that all of guest memory is pinned and we have a flat array mapping GPA to HPA which makes it simpler and quicker to index into that array (even with looking up the kernel page tables in vmalloc_to_phys) than it is to find the memslot, lock the rmap entry, look up the user page tables, and unlock the rmap entry. Note that the rmap pointer is initialized to NULL where declared (not in this patch). If a requested chunk of memory has not been preregistered, this will fall back to non-preregistered case and lock rmap. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> --- Changes: v4: * removed oneline inlines * now falls back to locking rmap if TCE list is not in preregistered memory v2: * updated the commit log with David's comment --- arch/powerpc/kvm/book3s_64_vio_hv.c | 58 +++++++++++++++++++++++++++---------- 1 file changed, 42 insertions(+), 16 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c index 918af76ab2b6..0f145fc7a3a5 100644 --- a/arch/powerpc/kvm/book3s_64_vio_hv.c +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c @@ -239,6 +239,7 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, long i, ret = H_SUCCESS; unsigned long tces, entry, ua = 0; unsigned long *rmap = NULL; + bool prereg = false; stt = kvmppc_find_table(vcpu->kvm, liobn); if (!stt) @@ -259,23 +260,47 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, if (ret != H_SUCCESS) return ret; - if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, &rmap)) - return H_TOO_HARD; + if (mm_iommu_preregistered(vcpu->kvm->mm)) { + /* + * We get here if guest memory was pre-registered which + * is normally VFIO case and gpa->hpa translation does not + * depend on hpt. + */ + struct mm_iommu_table_group_mem_t *mem; - rmap = (void *) vmalloc_to_phys(rmap); + if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, NULL)) + return H_TOO_HARD; - /* - * Synchronize with the MMU notifier callbacks in - * book3s_64_mmu_hv.c (kvm_unmap_hva_hv etc.). - * While we have the rmap lock, code running on other CPUs - * cannot finish unmapping the host real page that backs - * this guest real page, so we are OK to access the host - * real page. - */ - lock_rmap(rmap); - if (kvmppc_rm_ua_to_hpa(vcpu, ua, &tces)) { - ret = H_TOO_HARD; - goto unlock_exit; + mem = mm_iommu_lookup_rm(vcpu->kvm->mm, ua, IOMMU_PAGE_SIZE_4K); + if (mem) + prereg = mm_iommu_ua_to_hpa_rm(mem, ua, &tces) == 0; + } + + if (!prereg) { + /* + * This is usually a case of a guest with emulated devices only + * when TCE list is not in preregistered memory. + * We do not require memory to be preregistered in this case + * so lock rmap and do __find_linux_pte_or_hugepte(). + */ + if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, &rmap)) + return H_TOO_HARD; + + rmap = (void *) vmalloc_to_phys(rmap); + + /* + * Synchronize with the MMU notifier callbacks in + * book3s_64_mmu_hv.c (kvm_unmap_hva_hv etc.). + * While we have the rmap lock, code running on other CPUs + * cannot finish unmapping the host real page that backs + * this guest real page, so we are OK to access the host + * real page. + */ + lock_rmap(rmap); + if (kvmppc_rm_ua_to_hpa(vcpu, ua, &tces)) { + ret = H_TOO_HARD; + goto unlock_exit; + } } for (i = 0; i < npages; ++i) { @@ -289,7 +314,8 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, } unlock_exit: - unlock_rmap(rmap); + if (rmap) + unlock_rmap(rmap); return ret; } -- 2.11.0
WARNING: multiple messages have this Message-ID (diff)
From: Alexey Kardashevskiy <aik@ozlabs.ru> To: linuxppc-dev@lists.ozlabs.org Cc: Alexey Kardashevskiy <aik@ozlabs.ru>, Alex Williamson <alex.williamson@redhat.com>, David Gibson <david@gibson.dropbear.id.au>, Paul Mackerras <paulus@samba.org>, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org Subject: [PATCH kernel v10 08/10] KVM: PPC: Use preregistered memory API to access TCE list Date: Fri, 17 Mar 2017 05:09:57 +0000 [thread overview] Message-ID: <20170317050959.37312-9-aik@ozlabs.ru> (raw) In-Reply-To: <20170317050959.37312-1-aik@ozlabs.ru> VFIO on sPAPR already implements guest memory pre-registration when the entire guest RAM gets pinned. This can be used to translate the physical address of a guest page containing the TCE list from H_PUT_TCE_INDIRECT. This makes use of the pre-registrered memory API to access TCE list pages in order to avoid unnecessary locking on the KVM memory reverse map as we know that all of guest memory is pinned and we have a flat array mapping GPA to HPA which makes it simpler and quicker to index into that array (even with looking up the kernel page tables in vmalloc_to_phys) than it is to find the memslot, lock the rmap entry, look up the user page tables, and unlock the rmap entry. Note that the rmap pointer is initialized to NULL where declared (not in this patch). If a requested chunk of memory has not been preregistered, this will fall back to non-preregistered case and lock rmap. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> --- Changes: v4: * removed oneline inlines * now falls back to locking rmap if TCE list is not in preregistered memory v2: * updated the commit log with David's comment --- arch/powerpc/kvm/book3s_64_vio_hv.c | 58 +++++++++++++++++++++++++++---------- 1 file changed, 42 insertions(+), 16 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c index 918af76ab2b6..0f145fc7a3a5 100644 --- a/arch/powerpc/kvm/book3s_64_vio_hv.c +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c @@ -239,6 +239,7 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, long i, ret = H_SUCCESS; unsigned long tces, entry, ua = 0; unsigned long *rmap = NULL; + bool prereg = false; stt = kvmppc_find_table(vcpu->kvm, liobn); if (!stt) @@ -259,23 +260,47 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, if (ret != H_SUCCESS) return ret; - if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, &rmap)) - return H_TOO_HARD; + if (mm_iommu_preregistered(vcpu->kvm->mm)) { + /* + * We get here if guest memory was pre-registered which + * is normally VFIO case and gpa->hpa translation does not + * depend on hpt. + */ + struct mm_iommu_table_group_mem_t *mem; - rmap = (void *) vmalloc_to_phys(rmap); + if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, NULL)) + return H_TOO_HARD; - /* - * Synchronize with the MMU notifier callbacks in - * book3s_64_mmu_hv.c (kvm_unmap_hva_hv etc.). - * While we have the rmap lock, code running on other CPUs - * cannot finish unmapping the host real page that backs - * this guest real page, so we are OK to access the host - * real page. - */ - lock_rmap(rmap); - if (kvmppc_rm_ua_to_hpa(vcpu, ua, &tces)) { - ret = H_TOO_HARD; - goto unlock_exit; + mem = mm_iommu_lookup_rm(vcpu->kvm->mm, ua, IOMMU_PAGE_SIZE_4K); + if (mem) + prereg = mm_iommu_ua_to_hpa_rm(mem, ua, &tces) = 0; + } + + if (!prereg) { + /* + * This is usually a case of a guest with emulated devices only + * when TCE list is not in preregistered memory. + * We do not require memory to be preregistered in this case + * so lock rmap and do __find_linux_pte_or_hugepte(). + */ + if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, &rmap)) + return H_TOO_HARD; + + rmap = (void *) vmalloc_to_phys(rmap); + + /* + * Synchronize with the MMU notifier callbacks in + * book3s_64_mmu_hv.c (kvm_unmap_hva_hv etc.). + * While we have the rmap lock, code running on other CPUs + * cannot finish unmapping the host real page that backs + * this guest real page, so we are OK to access the host + * real page. + */ + lock_rmap(rmap); + if (kvmppc_rm_ua_to_hpa(vcpu, ua, &tces)) { + ret = H_TOO_HARD; + goto unlock_exit; + } } for (i = 0; i < npages; ++i) { @@ -289,7 +314,8 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, } unlock_exit: - unlock_rmap(rmap); + if (rmap) + unlock_rmap(rmap); return ret; } -- 2.11.0
next prev parent reply other threads:[~2017-03-17 5:10 UTC|newest] Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-03-17 5:09 [PATCH kernel v10 00/10] powerpc/kvm/vfio: Enable in-kernel acceleration Alexey Kardashevskiy 2017-03-17 5:09 ` Alexey Kardashevskiy 2017-03-17 5:09 ` [PATCH kernel v10 01/10] powerpc/mmu: Add real mode support for IOMMU preregistered memory Alexey Kardashevskiy 2017-03-17 5:09 ` Alexey Kardashevskiy 2017-03-17 5:09 ` [PATCH kernel v10 02/10] powerpc/powernv/iommu: Add real mode version of iommu_table_ops::exchange() Alexey Kardashevskiy 2017-03-17 5:09 ` Alexey Kardashevskiy 2017-03-17 5:09 ` [PATCH kernel v10 03/10] powerpc/iommu/vfio_spapr_tce: Cleanup iommu_table disposal Alexey Kardashevskiy 2017-03-17 5:09 ` Alexey Kardashevskiy 2017-03-17 5:09 ` [PATCH kernel v10 04/10] powerpc/vfio_spapr_tce: Add reference counting to iommu_table Alexey Kardashevskiy 2017-03-17 5:09 ` Alexey Kardashevskiy 2017-03-22 0:40 ` David Gibson 2017-03-22 0:40 ` David Gibson 2017-03-17 5:09 ` [PATCH kernel v10 05/10] KVM: PPC: Reserve KVM_CAP_SPAPR_TCE_VFIO capability number Alexey Kardashevskiy 2017-03-17 5:09 ` Alexey Kardashevskiy 2017-03-17 5:09 ` [PATCH kernel v10 06/10] KVM: PPC: Enable IOMMU_API for KVM_BOOK3S_64 permanently Alexey Kardashevskiy 2017-03-17 5:09 ` Alexey Kardashevskiy 2017-03-17 5:09 ` [PATCH kernel v10 07/10] KVM: PPC: Pass kvm* to kvmppc_find_table() Alexey Kardashevskiy 2017-03-17 5:09 ` Alexey Kardashevskiy 2017-03-17 5:09 ` Alexey Kardashevskiy [this message] 2017-03-17 5:09 ` [PATCH kernel v10 08/10] KVM: PPC: Use preregistered memory API to access TCE list Alexey Kardashevskiy 2017-03-17 5:09 ` [PATCH kernel v10 09/10] KVM: PPC: iommu: Unify TCE checking Alexey Kardashevskiy 2017-03-17 5:09 ` Alexey Kardashevskiy 2017-03-17 5:09 ` [PATCH kernel v10 10/10] KVM: PPC: VFIO: Add in-kernel acceleration for VFIO Alexey Kardashevskiy 2017-03-17 5:09 ` Alexey Kardashevskiy 2017-03-21 19:11 ` Alex Williamson 2017-03-21 19:11 ` Alex Williamson 2017-03-21 19:11 ` Alex Williamson
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