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Subject[PATCH 33/46] KVM: VMX: Introduce KVM_SET_IDENTITY_MAP_ADDR ioctl
Date
From: Sheng Yang <sheng@linux.intel.com>

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>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/vmx.c | 15 ++++++++++-----
arch/x86/kvm/x86.c | 19 +++++++++++++++++++
include/linux/kvm.h | 2 ++
4 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 08732d7..e210b21 100644
--- 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 c6256b9..686e1ab 100644
--- 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 18ce27f..2539e9a 100644
--- 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)
{
@@ -2169,6 +2177,17 @@ 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 230a91a..f8f8900 100644
--- 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)
--
1.6.4.1


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