KVM: x86: add read_phys to x86_emulate_ops

We want to read the physical memory when emulating RSM.

X86EMUL_IO_NEEDED is returned on all errors for consistency with other
helpers.
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_emulate.h

@@ -111,6 +111,16 @@ struct x86_emulate_ops {
 			unsigned int bytes,
 			struct x86_exception *fault);
 
+	/*
+	 * read_phys: Read bytes of standard (non-emulated/special) memory.
+	 *            Used for descriptor reading.
+	 *  @addr:  [IN ] Physical address from which to read.
+	 *  @val:   [OUT] Value read from memory.
+	 *  @bytes: [IN ] Number of bytes to read from memory.
+	 */
+	int (*read_phys)(struct x86_emulate_ctxt *ctxt, unsigned long addr,
+			void *val, unsigned int bytes);
+
 	/*
 	 * write_std: Write bytes of standard (non-emulated/special) memory.
 	 *            Used for descriptor writing.

arch/x86/kvm/x86.c

@@ -4089,6 +4089,15 @@ static int kvm_read_guest_virt_system(struct x86_emulate_ctxt *ctxt,
 	return kvm_read_guest_virt_helper(addr, val, bytes, vcpu, 0, exception);
 }
 
+static int kvm_read_guest_phys_system(struct x86_emulate_ctxt *ctxt,
+		unsigned long addr, void *val, unsigned int bytes)
+{
+	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
+	int r = kvm_vcpu_read_guest(vcpu, addr, val, bytes);
+
+	return r < 0 ? X86EMUL_IO_NEEDED : X86EMUL_CONTINUE;
+}
+
 int kvm_write_guest_virt_system(struct x86_emulate_ctxt *ctxt,
 				       gva_t addr, void *val,
 				       unsigned int bytes,
@@ -4824,6 +4833,7 @@ static const struct x86_emulate_ops emulate_ops = {
 	.write_gpr           = emulator_write_gpr,
 	.read_std            = kvm_read_guest_virt_system,
 	.write_std           = kvm_write_guest_virt_system,
+	.read_phys           = kvm_read_guest_phys_system,
 	.fetch               = kvm_fetch_guest_virt,
 	.read_emulated       = emulator_read_emulated,
 	.write_emulated      = emulator_write_emulated,