Re: [PATCH 5/5] KVM: PPC: Book3S: Eliminate some unnecessary checks

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Makes sense to me.

On Thu, Nov 23, 2017 at 08:01:05PM +1100, Paul Mackerras wrote:
In an excess of caution, commit 6f63e81bda98 ("KVM: PPC: Book3S: Add
MMIO emulation for FP and VSX instructions", 2017-02-21) included
checks for the case that vcpu->arch.mmio_vsx_copy_nums is less than
zero, even though its type is u8.  This causes a Coverity warning,
so we remove the check for < 0.  We also adjust the associated
comment to be more accurate ("4 or less" rather than "less than 4").

Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>

Reviewed-by: Darren Kenny <darren.kenny@xxxxxxxxxx>

---
arch/powerpc/kvm/powerpc.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 6b6c53c..c2c7ef3 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -1101,11 +1101,9 @@ int kvmppc_handle_vsx_load(struct kvm_run *run, struct kvm_vcpu *vcpu,
{
	enum emulation_result emulated = EMULATE_DONE;

-	/* Currently, mmio_vsx_copy_nums only allowed to be less than 4 */
-	if ( (vcpu->arch.mmio_vsx_copy_nums > 4) ||
-		(vcpu->arch.mmio_vsx_copy_nums < 0) ) {
+	/* Currently, mmio_vsx_copy_nums only allowed to be 4 or less */
+	if (vcpu->arch.mmio_vsx_copy_nums > 4)
		return EMULATE_FAIL;
-	}

	while (vcpu->arch.mmio_vsx_copy_nums) {
		emulated = __kvmppc_handle_load(run, vcpu, rt, bytes,
@@ -1247,11 +1245,9 @@ int kvmppc_handle_vsx_store(struct kvm_run *run, struct kvm_vcpu *vcpu,

	vcpu->arch.io_gpr = rs;

-	/* Currently, mmio_vsx_copy_nums only allowed to be less than 4 */
-	if ( (vcpu->arch.mmio_vsx_copy_nums > 4) ||
-		(vcpu->arch.mmio_vsx_copy_nums < 0) ) {
+	/* Currently, mmio_vsx_copy_nums only allowed to be 4 or less */
+	if (vcpu->arch.mmio_vsx_copy_nums > 4)
		return EMULATE_FAIL;
-	}

	while (vcpu->arch.mmio_vsx_copy_nums) {
		if (kvmppc_get_vsr_data(vcpu, rs, &val) == -1)
--
2.7.4




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