[PATCH v6 2/4] KVM: x86: report negative values from wrmsr emulation to userspace

[Maxim Levitsky]

This will allow the KVM to report such errors (e.g -ENOMEM)
to the userspace.

Signed-off-by: Maxim Levitsky <mlevi...@redhat.com>
---
 arch/x86/kvm/emulate.c | 7 +++++--
 arch/x86/kvm/x86.c     | 6 +++++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 1d450d7710d63..d855304f5a509 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3702,13 +3702,16 @@ static int em_dr_write(struct x86_emulate_ctxt *ctxt)
 static int em_wrmsr(struct x86_emulate_ctxt *ctxt)
 {
        u64 msr_data;
+       int ret;
 
        msr_data = (u32)reg_read(ctxt, VCPU_REGS_RAX)
                | ((u64)reg_read(ctxt, VCPU_REGS_RDX) << 32);
-       if (ctxt->ops->set_msr(ctxt, reg_read(ctxt, VCPU_REGS_RCX), msr_data))
+
+       ret = ctxt->ops->set_msr(ctxt, reg_read(ctxt, VCPU_REGS_RCX), msr_data);
+       if (ret > 0)
                return emulate_gp(ctxt, 0);
 
-       return X86EMUL_CONTINUE;
+       return ret < 0 ? X86EMUL_UNHANDLEABLE : X86EMUL_CONTINUE;
 }
 
 static int em_rdmsr(struct x86_emulate_ctxt *ctxt)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 063d70e736f7f..e4b07be450d4e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1612,8 +1612,12 @@ int kvm_emulate_wrmsr(struct kvm_vcpu *vcpu)
 {
        u32 ecx = kvm_rcx_read(vcpu);
        u64 data = kvm_read_edx_eax(vcpu);
+       int ret = kvm_set_msr(vcpu, ecx, data);
 
-       if (kvm_set_msr(vcpu, ecx, data)) {
+       if (ret < 0)
+               return ret;
+
+       if (ret > 0) {
                trace_kvm_msr_write_ex(ecx, data);
                kvm_inject_gp(vcpu, 0);
                return 1;
-- 
2.26.2