This patch includes a utility function for decoding pointer operands of VMX
instructions issued by L1 (a guest hypervisor)
Signed-off-by: Nadav Har'El n...@il.ibm.com
---
arch/x86/kvm/vmx.c | 53 +++
arch/x86/kvm/x86.c |3 +-
arch/x86/kvm/x86.h |4 +++
3 files changed, 59 insertions(+), 1 deletion(-)
--- .before/arch/x86/kvm/x86.c 2011-05-08 10:43:18.0 +0300
+++ .after/arch/x86/kvm/x86.c 2011-05-08 10:43:18.0 +0300
@@ -3815,7 +3815,7 @@ static int kvm_fetch_guest_virt(struct x
exception);
}
-static int kvm_read_guest_virt(struct x86_emulate_ctxt *ctxt,
+int kvm_read_guest_virt(struct x86_emulate_ctxt *ctxt,
gva_t addr, void *val, unsigned int bytes,
struct x86_exception *exception)
{
@@ -3825,6 +3825,7 @@ static int kvm_read_guest_virt(struct x8
return kvm_read_guest_virt_helper(addr, val, bytes, vcpu, access,
exception);
}
+EXPORT_SYMBOL_GPL(kvm_read_guest_virt);
static int kvm_read_guest_virt_system(struct x86_emulate_ctxt *ctxt,
gva_t addr, void *val, unsigned int bytes,
--- .before/arch/x86/kvm/x86.h 2011-05-08 10:43:18.0 +0300
+++ .after/arch/x86/kvm/x86.h 2011-05-08 10:43:18.0 +0300
@@ -81,4 +81,8 @@ int kvm_inject_realmode_interrupt(struct
void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data);
+int kvm_read_guest_virt(struct x86_emulate_ctxt *ctxt,
+ gva_t addr, void *val, unsigned int bytes,
+ struct x86_exception *exception);
+
#endif
--- .before/arch/x86/kvm/vmx.c 2011-05-08 10:43:18.0 +0300
+++ .after/arch/x86/kvm/vmx.c 2011-05-08 10:43:18.0 +0300
@@ -4254,6 +4254,59 @@ static int handle_vmoff(struct kvm_vcpu
}
/*
+ * Decode the memory-address operand of a vmx instruction, as recorded on an
+ * exit caused by such an instruction (run by a guest hypervisor).
+ * On success, returns 0. When the operand is invalid, returns 1 and throws
+ * #UD or #GP.
+ */
+static int get_vmx_mem_address(struct kvm_vcpu *vcpu,
+unsigned long exit_qualification,
+u32 vmx_instruction_info, gva_t *ret)
+{
+ /*
+* According to Vol. 3B, Information for VM Exits Due to Instruction
+* Execution, on an exit, vmx_instruction_info holds most of the
+* addressing components of the operand. Only the displacement part
+* is put in exit_qualification (see 3B, Basic VM-Exit Information).
+* For how an actual address is calculated from all these components,
+* refer to Vol. 1, Operand Addressing.
+*/
+ int scaling = vmx_instruction_info 3;
+ int addr_size = (vmx_instruction_info 7) 7;
+ bool is_reg = vmx_instruction_info (1u 10);
+ int seg_reg = (vmx_instruction_info 15) 7;
+ int index_reg = (vmx_instruction_info 18) 0xf;
+ bool index_is_valid = !(vmx_instruction_info (1u 22));
+ int base_reg = (vmx_instruction_info 23) 0xf;
+ bool base_is_valid = !(vmx_instruction_info (1u 27));
+
+ if (is_reg) {
+ kvm_queue_exception(vcpu, UD_VECTOR);
+ return 1;
+ }
+
+ /* Addr = segment_base + offset */
+ /* offset = base + [index * scale] + displacement */
+ *ret = vmx_get_segment_base(vcpu, seg_reg);
+ if (base_is_valid)
+ *ret += kvm_register_read(vcpu, base_reg);
+ if (index_is_valid)
+ *ret += kvm_register_read(vcpu, index_reg)scaling;
+ *ret += exit_qualification; /* holds the displacement */
+
+ if (addr_size == 1) /* 32 bit */
+ *ret = 0x;
+
+ /*
+* 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.
+*/
+ return 0;
+}
+
+/*
* The exit handlers return 1 if the exit was handled fully and guest execution
* may resume. Otherwise they set the kvm_run parameter to indicate what needs
* to be done to userspace and return 0.
--
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