[PATCH v19 014/130] KVM: Add KVM vcpu ioctl to pre-populate guest memory

isaku.yamahata
2024-02-26T08:27:46Z

From: Isaku Yamahata <isaku.yamahata@intel.com>

Add new ioctl KVM_MEMORY_MAPPING in the kvm common code. It iterates on the
memory range and call arch specific function. Add stub function as weak
symbol.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
v19:
- newly added
---
include/linux/kvm_host.h | 4 +++
include/uapi/linux/kvm.h | 10 ++++++
virt/kvm/kvm_main.c | 67 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 81 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0520cd8d03cc..eeaf4e73317c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2389,4 +2389,8 @@ static inline int kvm_gmem_get_pfn(struct kvm *kvm,
}
#endif /* CONFIG_KVM_PRIVATE_MEM */

+void kvm_arch_vcpu_pre_memory_mapping(struct kvm_vcpu *vcpu);
+int kvm_arch_vcpu_memory_mapping(struct kvm_vcpu *vcpu,
+ struct kvm_memory_mapping *mapping);
+
#endif
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index c3308536482b..5e2b28934aa9 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1155,6 +1155,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_MEMORY_ATTRIBUTES 233
#define KVM_CAP_GUEST_MEMFD 234
#define KVM_CAP_VM_TYPES 235
+#define KVM_CAP_MEMORY_MAPPING 236

#ifdef KVM_CAP_IRQ_ROUTING

@@ -2227,4 +2228,13 @@ struct kvm_create_guest_memfd {
__u64 reserved[6];
};

+#define KVM_MEMORY_MAPPING _IOWR(KVMIO, 0xd5, struct kvm_memory_mapping)
+
+struct kvm_memory_mapping {
+ __u64 base_gfn;
+ __u64 nr_pages;
+ __u64 flags;
+ __u64 source;
+};
+
#endif /* __LINUX_KVM_H */
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0349e1f241d1..2f0a8e28795e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4409,6 +4409,62 @@ static int kvm_vcpu_ioctl_get_stats_fd(struct kvm_vcpu *vcpu)
return fd;
}

+__weak void kvm_arch_vcpu_pre_memory_mapping(struct kvm_vcpu *vcpu)
+{
+}
+
+__weak int kvm_arch_vcpu_memory_mapping(struct kvm_vcpu *vcpu,
+ struct kvm_memory_mapping *mapping)
+{
+ return -EOPNOTSUPP;
+}
+
+static int kvm_vcpu_memory_mapping(struct kvm_vcpu *vcpu,
+ struct kvm_memory_mapping *mapping)
+{
+ bool added = false;
+ int idx, r = 0;
+
+ /* flags isn't used yet. */
+ if (mapping->flags)
+ return -EINVAL;
+
+ /* Sanity check */
+ if (!IS_ALIGNED(mapping->source, PAGE_SIZE) ||
+ !mapping->nr_pages ||
+ mapping->nr_pages & GENMASK_ULL(63, 63 - PAGE_SHIFT) ||
+ mapping->base_gfn + mapping->nr_pages <= mapping->base_gfn)
+ return -EINVAL;
+
+ vcpu_load(vcpu);
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
+ kvm_arch_vcpu_pre_memory_mapping(vcpu);
+
+ while (mapping->nr_pages) {
+ if (signal_pending(current)) {
+ r = -ERESTARTSYS;
+ break;
+ }
+
+ if (need_resched())
+ cond_resched();
+
+ r = kvm_arch_vcpu_memory_mapping(vcpu, mapping);
+ if (r)
+ break;
+
+ added = true;
+ }
+
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
+ vcpu_put(vcpu);
+
+ if (added && mapping->nr_pages > 0)
+ r = -EAGAIN;
+
+ return r;
+}
+
static long kvm_vcpu_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
@@ -4610,6 +4666,17 @@ static long kvm_vcpu_ioctl(struct file *filp,
r = kvm_vcpu_ioctl_get_stats_fd(vcpu);
break;
}
+ case KVM_MEMORY_MAPPING: {
+ struct kvm_memory_mapping mapping;
+
+ r = -EFAULT;
+ if (copy_from_user(&mapping, argp, sizeof(mapping)))
+ break;
+ r = kvm_vcpu_memory_mapping(vcpu, &mapping);
+ if (copy_to_user(argp, &mapping, sizeof(mapping)))
+ r = -EFAULT;
+ break;
+ }
default:
r = kvm_arch_vcpu_ioctl(filp, ioctl, arg);
}
--
2.25.1