On Mon, Dec 11, 2017 at 01:39:43PM +0100, Cornelia Huck wrote:

On Mon,  4 Dec 2017 21:35:33 +0100
Christoffer Dall [off-list ref] wrote:

quoted

From: Christoffer Dall <redacted>

Move vcpu_load() and vcpu_put() into the architecture specific
implementations of kvm_arch_vcpu_ioctl_set_guest_debug().

Reviewed-by: David Hildenbrand <redacted>
Signed-off-by: Christoffer Dall <redacted>
---
 arch/arm64/kvm/guest.c    | 15 ++++++++++++---
 arch/powerpc/kvm/book3s.c |  2 ++
 arch/powerpc/kvm/booke.c  | 19 +++++++++++++------
 arch/s390/kvm/kvm-s390.c  | 16 ++++++++++++----
 arch/x86/kvm/x86.c        |  4 +++-
 virt/kvm/kvm_main.c       |  2 --
 6 files changed, 42 insertions(+), 16 deletions(-)

quoted

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 1b491b89cd43..7cb0e2677e60 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c

@@ -2018,12 +2018,15 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 {
 	struct debug_reg *dbg_reg;
 	int n, b = 0, w = 0;
+	int ret = 0;
+
+	vcpu_load(vcpu);
 
 	if (!(dbg->control & KVM_GUESTDBG_ENABLE)) {
 		vcpu->arch.dbg_reg.dbcr0 = 0;
 		vcpu->guest_debug = 0;
 		kvm_guest_protect_msr(vcpu, MSR_DE, false);
-		return 0;
+		goto out;
 	}
 
 	kvm_guest_protect_msr(vcpu, MSR_DE, true);

@@ -2055,8 +2058,9 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 #endif
 
 	if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP))
-		return 0;
+		goto out;
 
+	ret = -EINVAL;
 	for (n = 0; n < (KVMPPC_BOOKE_IAC_NUM + KVMPPC_BOOKE_DAC_NUM); n++) {
 		uint64_t addr = dbg->arch.bp[n].addr;
 		uint32_t type = dbg->arch.bp[n].type;

@@ -2067,21 +2071,24 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 		if (type & ~(KVMPPC_DEBUG_WATCH_READ |
 			     KVMPPC_DEBUG_WATCH_WRITE |
 			     KVMPPC_DEBUG_BREAKPOINT))
-			return -EINVAL;
+			goto out;
 
 		if (type & KVMPPC_DEBUG_BREAKPOINT) {
 			/* Setting H/W breakpoint */
 			if (kvmppc_booke_add_breakpoint(dbg_reg, addr, b++))
-				return -EINVAL;
+				goto out;
 		} else {
 			/* Setting H/W watchpoint */
 			if (kvmppc_booke_add_watchpoint(dbg_reg, addr,
 							type, w++))
-				return -EINVAL;
+				goto out;
 		}
 	}
 
-	return 0;
+	ret = 0;

I would probably set the -EINVAL in the individual branches (so it is
clear that something is wrong, and it is not just a benign exit as in
the cases above), but your code is correct as well.

I think that's better as well actually.  I got probably got a little
used to that pattern after looking the main dispatcher function for a
while.  I'm happy to change it.

quoted

+out:
+	vcpu_put(vcpu);
+	return ret;
 }
 
 void kvmppc_booke_vcpu_load(struct kvm_vcpu *vcpu, int cpu)

In any case,

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Thanks!
-Christoffer