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 <[email protected]> --- --- .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); -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
