x86: Delay skip of emulated hypercall instruction

BugLink: http://bugs.launchpad.net/bugs/1794889
[ Upstream commit 6356ee0c9602004e0a3b4b2dad68ee2ee9385b17 ]

The IP increment should be done after the hypercall emulation, after
calling the various handlers. In this way, these handlers can accurately
identify the the IP of the VMCALL if they need it.

This patch keeps the same functionality for the Hyper-V handler which does
not use the return code of the standard kvm_skip_emulated_instruction()
call.

Signed-off-by: Marian Rotariu <mrotariu@bitdefender.com>
[Hyper-V hypercalls also need kvm_skip_emulated_instruction() - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index dc97f2544b6f8e840156725be640477cff3b6426..5d13abecb384514029d6991dc60efdc983a00d27 100644 (file)
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1223,7 +1223,7 @@ static int kvm_hv_hypercall_complete_userspace(struct kvm_vcpu *vcpu)
        struct kvm_run *run = vcpu->run;
 
        kvm_hv_hypercall_set_result(vcpu, run->hyperv.u.hcall.result);
-       return 1;
+       return kvm_skip_emulated_instruction(vcpu);
 }
 
 int kvm_hv_hypercall(struct kvm_vcpu *vcpu)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4b52bc86a2656267812bce4498fa2491754bdf90..5128952844b454d70ad326508cfd2046e4189bf6 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6421,12 +6421,13 @@ void kvm_vcpu_deactivate_apicv(struct kvm_vcpu *vcpu)
 int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 {
        unsigned long nr, a0, a1, a2, a3, ret;
-       int op_64_bit, r;
+       int op_64_bit;
 
-       r = kvm_skip_emulated_instruction(vcpu);
-
-       if (kvm_hv_hypercall_enabled(vcpu->kvm))
-               return kvm_hv_hypercall(vcpu);
+       if (kvm_hv_hypercall_enabled(vcpu->kvm)) {
+               if (!kvm_hv_hypercall(vcpu))
+                       return 0;
+               goto out;
+       }
 
        nr = kvm_register_read(vcpu, VCPU_REGS_RAX);
        a0 = kvm_register_read(vcpu, VCPU_REGS_RBX);
@@ -6447,7 +6448,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 
        if (kvm_x86_ops->get_cpl(vcpu) != 0) {
                ret = -KVM_EPERM;
-               goto out;
+               goto out_error;
        }
 
        switch (nr) {
@@ -6467,12 +6468,14 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
                ret = -KVM_ENOSYS;
                break;
        }
-out:
+out_error:
        if (!op_64_bit)
                ret = (u32)ret;
        kvm_register_write(vcpu, VCPU_REGS_RAX, ret);
+
+out:
        ++vcpu->stat.hypercalls;
-       return r;
+       return kvm_skip_emulated_instruction(vcpu);
 }
 EXPORT_SYMBOL_GPL(kvm_emulate_hypercall);