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Subject[PATCH v6 2/4] KVM: x86: report negative values from wrmsr emulation to userspace
Date
This will allow the KVM to report such errors (e.g -ENOMEM)
to the userspace.

Signed-off-by: Maxim Levitsky <mlevitsk@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
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