[PATCH v2 2/2] KVM: PPC: Book3S HV: XIVE: Fix potential page leak on error path

[Greg Kurz]

We need to check the host page size is big enough to accomodate the
EQ. Let's do this before taking a reference on the EQ page to avoid
a potential leak if the check fails.

Cc: sta...@vger.kernel.org # v5.2
Fixes: 13ce3297c576 ("KVM: PPC: Book3S HV: XIVE: Add controls for the EQ 
configuration")
Signed-off-by: Greg Kurz <gr...@kaod.org>
---
 arch/powerpc/kvm/book3s_xive_native.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_xive_native.c 
b/arch/powerpc/kvm/book3s_xive_native.c
index 0e1fc5a16729..d83adb1e1490 100644
--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -630,12 +630,6 @@ static int kvmppc_xive_native_set_queue_config(struct 
kvmppc_xive *xive,
 
        srcu_idx = srcu_read_lock(&kvm->srcu);
        gfn = gpa_to_gfn(kvm_eq.qaddr);
-       page = gfn_to_page(kvm, gfn);
-       if (is_error_page(page)) {
-               srcu_read_unlock(&kvm->srcu, srcu_idx);
-               pr_err("Couldn't get queue page %llx!\n", kvm_eq.qaddr);
-               return -EINVAL;
-       }
 
        page_size = kvm_host_page_size(kvm, gfn);
        if (1ull << kvm_eq.qshift > page_size) {
@@ -644,6 +638,13 @@ static int kvmppc_xive_native_set_queue_config(struct 
kvmppc_xive *xive,
                return -EINVAL;
        }
 
+       page = gfn_to_page(kvm, gfn);
+       if (is_error_page(page)) {
+               srcu_read_unlock(&kvm->srcu, srcu_idx);
+               pr_err("Couldn't get queue page %llx!\n", kvm_eq.qaddr);
+               return -EINVAL;
+       }
+
        qaddr = page_to_virt(page) + (kvm_eq.qaddr & ~PAGE_MASK);
        srcu_read_unlock(&kvm->srcu, srcu_idx);