KVM: VMX: Introduce KVM_SET_IDENTITY_MAP_ADDR ioctl

Now KVM allow guest to modify guest's physical address of EPT's identity mapping page.

(change from v1, discard unnecessary check, change ioctl to accept parameter
address rather than value)

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 08732d7b6d98990ef16540d5fda5b378c723c590..e210b218df44ead2faff54c0716741e6928d9434 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -411,6 +411,7 @@ struct kvm_arch{
 
        struct page *ept_identity_pagetable;
        bool ept_identity_pagetable_done;
+       gpa_t ept_identity_map_addr;
 
        unsigned long irq_sources_bitmap;
        unsigned long irq_states[KVM_IOAPIC_NUM_PINS];

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c6256b98f078ae265a5ed14b7208779dcf497c1f..686e1abb68163f56b956471198dd67932cc3f26f 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1719,7 +1719,7 @@ static void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
                eptp = construct_eptp(cr3);
                vmcs_write64(EPT_POINTER, eptp);
                guest_cr3 = is_paging(vcpu) ? vcpu->arch.cr3 :
-                       VMX_EPT_IDENTITY_PAGETABLE_ADDR;
+                       vcpu->kvm->arch.ept_identity_map_addr;
        }
 
        vmx_flush_tlb(vcpu);
@@ -2122,7 +2122,7 @@ static int init_rmode_identity_map(struct kvm *kvm)
        if (likely(kvm->arch.ept_identity_pagetable_done))
                return 1;
        ret = 0;
-       identity_map_pfn = VMX_EPT_IDENTITY_PAGETABLE_ADDR >> PAGE_SHIFT;
+       identity_map_pfn = kvm->arch.ept_identity_map_addr >> PAGE_SHIFT;
        r = kvm_clear_guest_page(kvm, identity_map_pfn, 0, PAGE_SIZE);
        if (r < 0)
                goto out;
@@ -2191,14 +2191,15 @@ static int alloc_identity_pagetable(struct kvm *kvm)
                goto out;
        kvm_userspace_mem.slot = IDENTITY_PAGETABLE_PRIVATE_MEMSLOT;
        kvm_userspace_mem.flags = 0;
-       kvm_userspace_mem.guest_phys_addr = VMX_EPT_IDENTITY_PAGETABLE_ADDR;
+       kvm_userspace_mem.guest_phys_addr =
+               kvm->arch.ept_identity_map_addr;
        kvm_userspace_mem.memory_size = PAGE_SIZE;
        r = __kvm_set_memory_region(kvm, &kvm_userspace_mem, 0);
        if (r)
                goto out;
 
        kvm->arch.ept_identity_pagetable = gfn_to_page(kvm,
-                       VMX_EPT_IDENTITY_PAGETABLE_ADDR >> PAGE_SHIFT);
+                       kvm->arch.ept_identity_map_addr >> PAGE_SHIFT);
 out:
        up_write(&kvm->slots_lock);
        return r;
@@ -3814,9 +3815,13 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
                if (alloc_apic_access_page(kvm) != 0)
                        goto free_vmcs;
 
-       if (enable_ept)
+       if (enable_ept) {
+               if (!kvm->arch.ept_identity_map_addr)
+                       kvm->arch.ept_identity_map_addr =
+                               VMX_EPT_IDENTITY_PAGETABLE_ADDR;
                if (alloc_identity_pagetable(kvm) != 0)
                        goto free_vmcs;
+       }
 
        return &vmx->vcpu;
 

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c7ec0c921c01d819e64fe71031b6061c3d44e079..f4cb1baaa04b5ccd337274e8d620c3999e4eec6c 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1206,6 +1206,7 @@ int kvm_dev_ioctl_check_extension(long ext)
        case KVM_CAP_IOEVENTFD:
        case KVM_CAP_PIT2:
        case KVM_CAP_PIT_STATE2:
+       case KVM_CAP_SET_IDENTITY_MAP_ADDR:
                r = 1;
                break;
        case KVM_CAP_COALESCED_MMIO:
@@ -1906,6 +1907,13 @@ static int kvm_vm_ioctl_set_tss_addr(struct kvm *kvm, unsigned long addr)
        return ret;
 }
 
+static int kvm_vm_ioctl_set_identity_map_addr(struct kvm *kvm,
+                                             u64 ident_addr)
+{
+       kvm->arch.ept_identity_map_addr = ident_addr;
+       return 0;
+}
+
 static int kvm_vm_ioctl_set_nr_mmu_pages(struct kvm *kvm,
                                          u32 kvm_nr_mmu_pages)
 {
@@ -2173,6 +2181,17 @@ long kvm_arch_vm_ioctl(struct file *filp,
                if (r < 0)
                        goto out;
                break;
+       case KVM_SET_IDENTITY_MAP_ADDR: {
+               u64 ident_addr;
+
+               r = -EFAULT;
+               if (copy_from_user(&ident_addr, argp, sizeof ident_addr))
+                       goto out;
+               r = kvm_vm_ioctl_set_identity_map_addr(kvm, ident_addr);
+               if (r < 0)
+                       goto out;
+               break;
+       }
        case KVM_SET_MEMORY_REGION: {
                struct kvm_memory_region kvm_mem;
                struct kvm_userspace_memory_region kvm_userspace_mem;

diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 230a91aa61c9d23e40f896717b7f8b12bdc82928..f8f8900fc5ecbcdf22fe6ae274537830f5c2b181 100644 (file)
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -435,6 +435,7 @@ struct kvm_ioeventfd {
 #define KVM_CAP_PIT_STATE2 35
 #endif
 #define KVM_CAP_IOEVENTFD 36
+#define KVM_CAP_SET_IDENTITY_MAP_ADDR 37
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -512,6 +513,7 @@ struct kvm_irqfd {
 #define KVM_SET_USER_MEMORY_REGION _IOW(KVMIO, 0x46,\
                                        struct kvm_userspace_memory_region)
 #define KVM_SET_TSS_ADDR          _IO(KVMIO, 0x47)
+#define KVM_SET_IDENTITY_MAP_ADDR _IOW(KVMIO, 0x48, __u64)
 /* Device model IOC */
 #define KVM_CREATE_IRQCHIP       _IO(KVMIO,  0x60)
 #define KVM_IRQ_LINE             _IOW(KVMIO, 0x61, struct kvm_irq_level)