On 07/15/2013 06:11:16 AM, Bharat Bhushan wrote:
Exit to guest user space if kvm does not implement the hcall.
Signed-off-by: Bharat Bhushan <bharat.bhushan@xxxxxxxxxxxxx>
---
arch/powerpc/kvm/booke.c | 47
+++++++++++++++++++++++++++++++++++++------
arch/powerpc/kvm/powerpc.c | 1 +
include/uapi/linux/kvm.h | 1 +
3 files changed, 42 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 17722d8..c8b41b4 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -1005,9 +1005,25 @@ int kvmppc_handle_exit(struct kvm_run *run,
struct kvm_vcpu *vcpu,
break;
#ifdef CONFIG_KVM_BOOKE_HV
- case BOOKE_INTERRUPT_HV_SYSCALL:
+ case BOOKE_INTERRUPT_HV_SYSCALL: {
+ int i;
if (!(vcpu->arch.shared->msr & MSR_PR)) {
- kvmppc_set_gpr(vcpu, 3, kvmppc_kvm_pv(vcpu));
+ r = kvmppc_kvm_pv(vcpu);
+ if (r != EV_UNIMPLEMENTED) {
+ /* except unimplemented return to guest
*/
+ kvmppc_set_gpr(vcpu, 3, r);
+ kvmppc_account_exit(vcpu,
SYSCALL_EXITS);
+ r = RESUME_GUEST;
+ break;
+ }
+ /* Exit to userspace for unimplemented hcalls
in kvm */
+ run->epapr_hcall.nr = kvmppc_get_gpr(vcpu, 11);
+ run->epapr_hcall.ret = 0;
+ for (i = 0; i < 8; i++)
+ run->epapr_hcall.args[i] =
kvmppc_get_gpr(vcpu, 3 + i);
You need to clear the upper half of each register if CONFIG_PPC64=y and
MSR_CM is not set.
+ vcpu->arch.hcall_needed = 1;
The existing code for hcall_needed restores 9 return arguments, rather
than the 8 that are defined for this interface. Thus, you'll be
restoring one word of padding into the guest -- which could be
arbitrary userspace data that shouldn't be leaked. r12 is volatile in
the ePAPR hcall ABI so simply clobbering it isn't a problem, though.
-Scott
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