On Sun, Jun 13, 2010 at 03:26:09PM +0300, Nadav Har'El wrote:
> 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;
Isn't zero a legitimate address for vmx operation?
> + }
> +
> + 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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Gleb.
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