This patch includes a couple of utility functions for extracting pointer
operands of VMX instructions issued by L1 (a guest hypervisor), and
translating guest-given vmcs12 virtual addresses to guest-physical addresses.
Signed-off-by: Nadav Har'El <nyh@xxxxxxxxxx>
---
--- .before/arch/x86/kvm/x86.c 2010-06-13 15:01:29.000000000 +0300
+++ .after/arch/x86/kvm/x86.c 2010-06-13 15:01:29.000000000 +0300
@@ -3286,13 +3286,14 @@ static int kvm_fetch_guest_virt(gva_t ad
access | PFERR_FETCH_MASK, error);
}
-static int kvm_read_guest_virt(gva_t addr, void *val, unsigned int bytes,
+int kvm_read_guest_virt(gva_t addr, void *val, unsigned int bytes,
struct kvm_vcpu *vcpu, u32 *error)
{
u32 access = (kvm_x86_ops->get_cpl(vcpu) == 3) ? PFERR_USER_MASK : 0;
return kvm_read_guest_virt_helper(addr, val, bytes, vcpu, access,
error);
}
+EXPORT_SYMBOL_GPL(kvm_read_guest_virt);
static int kvm_read_guest_virt_system(gva_t addr, void *val, unsigned int bytes,
struct kvm_vcpu *vcpu, u32 *error)
--- .before/arch/x86/kvm/x86.h 2010-06-13 15:01:29.000000000 +0300
+++ .after/arch/x86/kvm/x86.h 2010-06-13 15:01:29.000000000 +0300
@@ -75,6 +75,9 @@ static inline struct kvm_mem_aliases *kv
void kvm_before_handle_nmi(struct kvm_vcpu *vcpu);
void kvm_after_handle_nmi(struct kvm_vcpu *vcpu);
+int kvm_read_guest_virt(gva_t addr, void *val, unsigned int bytes,
+ struct kvm_vcpu *vcpu, u32 *error);
+
extern int nested;
#endif
--- .before/arch/x86/kvm/vmx.c 2010-06-13 15:01:29.000000000 +0300
+++ .after/arch/x86/kvm/vmx.c 2010-06-13 15:01:29.000000000 +0300
@@ -3654,6 +3654,86 @@ static int handle_vmoff(struct kvm_vcpu
return 1;
}
+/*
+ * Decode the memory-address operand of a vmx instruction, according to the
+ * Intel spec.
+ */
+#define VMX_OPERAND_SCALING(vii) ((vii) & 3)
+#define VMX_OPERAND_ADDR_SIZE(vii) (((vii) >> 7) & 7)
+#define VMX_OPERAND_IS_REG(vii) ((vii) & (1u << 10))
+#define VMX_OPERAND_SEG_REG(vii) (((vii) >> 15) & 7)
+#define VMX_OPERAND_INDEX_REG(vii) (((vii) >> 18) & 0xf)
+#define VMX_OPERAND_INDEX_INVALID(vii) ((vii) & (1u << 22))
+#define VMX_OPERAND_BASE_REG(vii) (((vii) >> 23) & 0xf)
+#define VMX_OPERAND_BASE_INVALID(vii) ((vii) & (1u << 27))
+#define VMX_OPERAND_REG(vii) (((vii) >> 3) & 0xf)
+#define VMX_OPERAND_REG2(vii) (((vii) >> 28) & 0xf)
+static gva_t get_vmx_mem_address(struct kvm_vcpu *vcpu,
+ unsigned long exit_qualification,
+ u32 vmx_instruction_info)
+{
+ int scaling = VMX_OPERAND_SCALING(vmx_instruction_info);
+ int addr_size = VMX_OPERAND_ADDR_SIZE(vmx_instruction_info);
+ bool is_reg = VMX_OPERAND_IS_REG(vmx_instruction_info);
+ int seg_reg = VMX_OPERAND_SEG_REG(vmx_instruction_info);
+ int index_reg = VMX_OPERAND_SEG_REG(vmx_instruction_info);
+ bool index_is_valid = !VMX_OPERAND_INDEX_INVALID(vmx_instruction_info);
+ int base_reg = VMX_OPERAND_BASE_REG(vmx_instruction_info);
+ bool base_is_valid = !VMX_OPERAND_BASE_INVALID(vmx_instruction_info);
+ gva_t addr;
+
+ if (is_reg) {
+ kvm_queue_exception(vcpu, UD_VECTOR);
+ return 0;
+ }
+
+ switch (addr_size) {
+ case 1: /* 32 bit. high bits are undefined according to the spec: */
+ exit_qualification &= 0xffffffff;
+ break;
+ case 2: /* 64 bit */
+ break;
+ default: /* addr_size=0 means 16 bit */
+ return 0;
+ }
+
+ /* Addr = segment_base + offset */
+ /* offfset = Base + [Index * Scale] + Displacement */
+ addr = vmx_get_segment_base(vcpu, seg_reg);
+ if (base_is_valid)
+ addr += kvm_register_read(vcpu, base_reg);
+ if (index_is_valid)
+ addr += kvm_register_read(vcpu, index_reg)<<scaling;
+ addr += exit_qualification; /* holds the displacement */
+
+ return addr;
+}
+
+static int read_guest_vmcs_gpa(struct kvm_vcpu *vcpu, gpa_t *gpap)
+{
+ int r;
+ gva_t gva = get_vmx_mem_address(vcpu,
+ vmcs_readl(EXIT_QUALIFICATION),
+ vmcs_read32(VMX_INSTRUCTION_INFO));
+ if (gva == 0)
+ return 1;
+ *gpap = 0;
+ r = kvm_read_guest_virt(gva, gpap, sizeof(*gpap), vcpu, NULL);
+ if (r) {
+ printk(KERN_ERR "%s cannot read guest vmcs addr %lx : %d\n",
+ __func__, gva, r);
+ return r;
+ }
+ /* According to the spec, VMCS addresses must be 4K aligned */
+ if (!IS_ALIGNED(*gpap, PAGE_SIZE)) {
+ printk(KERN_DEBUG "%s addr %llx not aligned\n",
+ __func__, *gpap);
+ return 1;
+ }
+
+ return 0;
+}
+
static int handle_invlpg(struct kvm_vcpu *vcpu)
{
unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
--
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