linux-kernel - [Patch v4 10/18] KVM: x86/mmu: Add per VM NUMA aware page table capability

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Date:   Mon,  6 Mar 2023 14:41:19 -0800
From:   Vipin Sharma <vipinsh@...gle.com>
To:     seanjc@...gle.com, pbonzini@...hat.com, bgardon@...gle.com,
        dmatlack@...gle.com
Cc:     jmattson@...gle.com, mizhang@...gle.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Vipin Sharma <vipinsh@...gle.com>
Subject: [Patch v4 10/18] KVM: x86/mmu: Add per VM NUMA aware page table capability

Add KVM_CAP_NUMA_AWARE_PAGE_TABLE capability. This capability enables a
VM to allocate its page tables, specifically lower level page tables, on
the NUMA node of underlying leaf physical page pointed by the page table
entry.

This patch is only adding this option, future patches will use the
boolean numa_aware_page_table to allocate page tables on appropriate
NUMA node.

For now this capability is for x86 only, it can be extended to other
architecture in future if needed.

Signed-off-by: Vipin Sharma <vipinsh@...gle.com>
---
 arch/x86/include/asm/kvm_host.h |  6 ++++++
 arch/x86/kvm/x86.c              | 10 ++++++++++
 include/uapi/linux/kvm.h        |  1 +
 3 files changed, 17 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 185719dbeb81..64de083cd6b9 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1467,6 +1467,12 @@ struct kvm_arch {
 	 */
 #define SPLIT_DESC_CACHE_MIN_NR_OBJECTS (SPTE_ENT_PER_PAGE + 1)
 	struct kvm_mmu_memory_cache split_desc_cache;
+
+	/*
+	 * If true then allocate page tables near to underlying physical page
+	 * NUMA node.
+	 */
+	bool numa_aware_page_table;
 };
 
 struct kvm_vm_stat {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f706621c35b8..71728abd7f92 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4425,6 +4425,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_VAPIC:
 	case KVM_CAP_ENABLE_CAP:
 	case KVM_CAP_VM_DISABLE_NX_HUGE_PAGES:
+	case KVM_CAP_NUMA_AWARE_PAGE_TABLE:
 		r = 1;
 		break;
 	case KVM_CAP_EXIT_HYPERCALL:
@@ -6391,6 +6392,15 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 		}
 		mutex_unlock(&kvm->lock);
 		break;
+	case KVM_CAP_NUMA_AWARE_PAGE_TABLE:
+		r = -EINVAL;
+		mutex_lock(&kvm->lock);
+		if (!kvm->created_vcpus) {
+			kvm->arch.numa_aware_page_table = true;
+			r = 0;
+		}
+		mutex_unlock(&kvm->lock);
+		break;
 	default:
 		r = -EINVAL;
 		break;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index d77aef872a0a..5f367a93762a 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1184,6 +1184,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_S390_PROTECTED_ASYNC_DISABLE 224
 #define KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP 225
 #define KVM_CAP_PMU_EVENT_MASKED_EVENTS 226
+#define KVM_CAP_NUMA_AWARE_PAGE_TABLE 227
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
-- 
2.40.0.rc0.216.gc4246ad0f0-goog