From: Metin Kaya <metikaya@xxxxxxxxxx>
This patch introduces compat version of struct sched_poll for
SCHEDOP_poll sub-operation of sched_op hypercall, reads correct amount
of data (16 bytes in 32-bit case, 24 bytes otherwise) by using new
compat_sched_poll struct, copies it to sched_poll properly, and lets
rest of the code run as is.
Signed-off-by: Metin Kaya <metikaya@xxxxxxxxxx>
---
arch/x86/kvm/xen.c | 31 +++++++++++++++++++++++++++----
arch/x86/kvm/xen.h | 7 +++++++
2 files changed, 34 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 7d01983d1087..2d0a5d2ca6f1 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -998,20 +998,43 @@ static bool kvm_xen_schedop_poll(struct kvm_vcpu *vcpu, bool longmode,
evtchn_port_t port, *ports;
gpa_t gpa;
- if (!longmode || !lapic_in_kernel(vcpu) ||
+ if (!lapic_in_kernel(vcpu) ||
!(vcpu->kvm->arch.xen_hvm_config.flags & KVM_XEN_HVM_CONFIG_EVTCHN_SEND))
return false;
idx = srcu_read_lock(&vcpu->kvm->srcu);
gpa = kvm_mmu_gva_to_gpa_system(vcpu, param, NULL);
srcu_read_unlock(&vcpu->kvm->srcu, idx);
-
- if (!gpa || kvm_vcpu_read_guest(vcpu, gpa, &sched_poll,
- sizeof(sched_poll))) {
+ if (!gpa) {
*r = -EFAULT;
return true;
}
+ if (IS_ENABLED(CONFIG_64BIT) && longmode) {
+ if (kvm_vcpu_read_guest(vcpu, gpa, &sched_poll,
+ sizeof(sched_poll))) {
+ *r = -EFAULT;
+ return true;
+ }
+ } else {
+ struct compat_sched_poll sp;
+
+ /*
+ * Sanity check that __packed trick works fine and size of
+ * compat_sched_poll is 16 bytes just like in the real Xen
+ * 32-bit case.
+ */
+ BUILD_BUG_ON(sizeof(struct compat_sched_poll) != 16);
+
+ if (kvm_vcpu_read_guest(vcpu, gpa, &sp, sizeof(sp))) {
+ *r = -EFAULT;
+ return true;
+ }
+ sched_poll.ports = (evtchn_port_t *)(unsigned long)(sp.ports);
+ sched_poll.nr_ports = sp.nr_ports;
+ sched_poll.timeout = sp.timeout;
+ }
+
if (unlikely(sched_poll.nr_ports > 1)) {
/* Xen (unofficially) limits number of pollers to 128 */
if (sched_poll.nr_ports > 128) {
diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h
index ee5c4ae0755c..8b36d346fc9c 100644
--- a/arch/x86/kvm/xen.h
+++ b/arch/x86/kvm/xen.h
@@ -196,6 +196,13 @@ struct compat_shared_info {
struct compat_arch_shared_info arch;
};
+struct compat_sched_poll {
+ /* This is actually a guest virtual address which points to ports. */
+ uint32_t ports;
+ unsigned int nr_ports;
+ uint64_t timeout;
+} __packed;
+
#define COMPAT_EVTCHN_2L_NR_CHANNELS (8 * \
sizeof_field(struct compat_shared_info, \
evtchn_pending))
--
2.32.0
