On 17/04/2015 04:22, Eugene Korenevsky wrote: > According to Intel SDM several checks must be applied for memory operands > of VMX instructions. > > Long mode: #GP(0) or #SS(0) depending on the segment must be thrown > if the memory address is in a non-canonical form. > > Protected mode, checks in chronological order: > - The segment type must be checked with access type (read or write) taken > into account. > For write access: #GP(0) must be generated if the destination operand > is located in a read-only data segment or any code segment. > For read access: #GP(0) must be generated if if the source operand is > located in an execute-only code segment. > - Usability of the segment must be checked. #GP(0) or #SS(0) depending on the > segment must be thrown if the segment is unusable. > - Limit check. #GP(0) or #SS(0) depending on the segment must be > thrown if the memory operand effective address is outside the segment > limit. > > > Signed-off-by: Eugene Korenevsky <[email protected]> > --- > arch/x86/kvm/vmx.c | 77 > ++++++++++++++++++++++++++++++++++++++++++------------ > 1 file changed, 61 insertions(+), 16 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 8c14d6a..08a721e 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -6404,8 +6404,12 @@ static enum hrtimer_restart > vmx_preemption_timer_fn(struct hrtimer *timer) > */ > static int get_vmx_mem_address(struct kvm_vcpu *vcpu, > unsigned long exit_qualification, > - u32 vmx_instruction_info, gva_t *ret) > + u32 vmx_instruction_info, bool wr, gva_t *ret) > { > + gva_t off; > + bool exn; > + struct kvm_segment s; > + > /* > * According to Vol. 3B, "Information for VM Exits Due to Instruction > * Execution", on an exit, vmx_instruction_info holds most of the > @@ -6430,22 +6434,63 @@ static int get_vmx_mem_address(struct kvm_vcpu *vcpu, > > /* Addr = segment_base + offset */ > /* offset = base + [index * scale] + displacement */ > - *ret = vmx_get_segment_base(vcpu, seg_reg); > + off = exit_qualification; /* holds the displacement */ > if (base_is_valid) > - *ret += kvm_register_read(vcpu, base_reg); > + off += kvm_register_read(vcpu, base_reg); > if (index_is_valid) > - *ret += kvm_register_read(vcpu, index_reg)<<scaling; > - *ret += exit_qualification; /* holds the displacement */ > + off += kvm_register_read(vcpu, index_reg)<<scaling; > + vmx_get_segment(vcpu, &s, seg_reg); > + *ret = s.base + off; > > if (addr_size == 1) /* 32 bit */ > *ret &= 0xffffffff; > > - /* > - * TODO: throw #GP (and return 1) in various cases that the VM* > - * instructions require it - e.g., offset beyond segment limit, > - * unusable or unreadable/unwritable segment, non-canonical 64-bit > - * address, and so on. Currently these are not checked. > - */ > + /* Checks for #GP/#SS exceptions. */ > + exn = false; > + if (is_protmode(vcpu)) { > + /* Protected mode: apply checks for segment validity in the > + * following order: > + * - segment type check (#GP(0) may be thrown) > + * - usability check (#GP(0)/#SS(0)) > + * - limit check (#GP(0)/#SS(0)) > + */ > + if (wr) > + /* #GP(0) if the destination operand is located in a > + * read-only data segment or any code segment. > + */ > + exn = ((s.type & 0xa) == 0 || (s.type & 8)); > + else > + /* #GP(0) if the source operand is located in an > + * execute-only code segment > + */ > + exn = ((s.type & 0xa) == 8); > + } > + if (exn) { > + kvm_queue_exception_e(vcpu, GP_VECTOR, 0); > + return 1; > + } > + if (is_long_mode(vcpu)) { > + /* Long mode: #GP(0)/#SS(0) if the memory address is in a > + * non-canonical form. This is an only check for long mode. > + */ > + exn = is_noncanonical_address(*ret); > + } else if (is_protmode(vcpu)) { > + /* Protected mode: #GP(0)/#SS(0) if the segment is unusable. > + */ > + exn = (s.unusable != 0); > + /* Protected mode: #GP(0)/#SS(0) if the memory > + * operand is outside the segment limit. > + */ > + exn = exn || (off + sizeof(u64) > s.limit); > + } > + if (exn) { > + kvm_queue_exception_e(vcpu, > + seg_reg == VCPU_SREG_SS ? > + SS_VECTOR : GP_VECTOR, > + 0); > + return 1; > + } > + > return 0; > } > > @@ -6467,7 +6512,7 @@ static int nested_vmx_check_vmptr(struct kvm_vcpu > *vcpu, int exit_reason, > int maxphyaddr = cpuid_maxphyaddr(vcpu); > > if (get_vmx_mem_address(vcpu, vmcs_readl(EXIT_QUALIFICATION), > - vmcs_read32(VMX_INSTRUCTION_INFO), &gva)) > + vmcs_read32(VMX_INSTRUCTION_INFO), false, &gva)) > return 1; > > if (kvm_read_guest_virt(&vcpu->arch.emulate_ctxt, gva, &vmptr, > @@ -6995,7 +7040,7 @@ static int handle_vmread(struct kvm_vcpu *vcpu) > field_value); > } else { > if (get_vmx_mem_address(vcpu, exit_qualification, > - vmx_instruction_info, &gva)) > + vmx_instruction_info, true, &gva)) > return 1; > /* _system ok, as nested_vmx_check_permission verified cpl=0 */ > kvm_write_guest_virt_system(&vcpu->arch.emulate_ctxt, gva, > @@ -7032,7 +7077,7 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu) > (((vmx_instruction_info) >> 3) & 0xf)); > else { > if (get_vmx_mem_address(vcpu, exit_qualification, > - vmx_instruction_info, &gva)) > + vmx_instruction_info, false, &gva)) > return 1; > if (kvm_read_guest_virt(&vcpu->arch.emulate_ctxt, gva, > &field_value, (is_64_bit_mode(vcpu) ? 8 : 4), &e)) { > @@ -7124,7 +7169,7 @@ static int handle_vmptrst(struct kvm_vcpu *vcpu) > return 1; > > if (get_vmx_mem_address(vcpu, exit_qualification, > - vmx_instruction_info, &vmcs_gva)) > + vmx_instruction_info, true, &vmcs_gva)) > return 1; > /* ok to use *_system, as nested_vmx_check_permission verified cpl=0 */ > if (kvm_write_guest_virt_system(&vcpu->arch.emulate_ctxt, vmcs_gva, > @@ -7180,7 +7225,7 @@ static int handle_invept(struct kvm_vcpu *vcpu) > * operand is read even if it isn't needed (e.g., for type==global) > */ > if (get_vmx_mem_address(vcpu, vmcs_readl(EXIT_QUALIFICATION), > - vmx_instruction_info, &gva)) > + vmx_instruction_info, false, &gva)) > return 1; > if (kvm_read_guest_virt(&vcpu->arch.emulate_ctxt, gva, &operand, > sizeof(operand), &e)) { >
Applied, thanks. Paolo -- 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
