pseries: Don't test for MSR_PR for hypercalls under KVM

PAPR hypercalls should only be invoked from the guest kernel, not guest
user programs, that is, with MSR[PR]=0.  Currently we check this in
spapr_hypercall, returning H_PRIVILEGE if MSR[PR]=1.

However, under KVM the state of MSR[PR] is already checked by the host
kernel before passing the hypercall to qemu, making this check redundant.
Worse, however, we don't generally synchronize KVM and qemu state on the
hypercall path, meaning that qemu could incorrectly reject a hypercall
because it has a stale MSR value.

This patch fixes the problem by moving the privilege test exclusively to
the TCG hypercall path.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
CC: qemu-stable@nongnu.org
Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/hw/spapr.c b/hw/spapr.c
index a8bd3c1ae65ec5232e7cf81b83a70203fa72512d..ab227a00936db0b17eb4e0b73c3fd292db1f2e95 100644 (file)
--- a/hw/spapr.c
+++ b/hw/spapr.c
@@ -573,7 +573,12 @@ static uint64_t translate_kernel_address(void *opaque, uint64_t addr)
 
 static void emulate_spapr_hypercall(CPUPPCState *env)
 {
-    env->gpr[3] = spapr_hypercall(env, env->gpr[3], &env->gpr[4]);
+    if (msr_pr) {
+        hcall_dprintf("Hypercall made with MSR[PR]=1\n");
+        env->gpr[3] = H_PRIVILEGE;
+    } else {
+        env->gpr[3] = spapr_hypercall(env, env->gpr[3], &env->gpr[4]);
+    }
 }
 
 static void spapr_reset_htab(sPAPREnvironment *spapr)

diff --git a/hw/spapr_hcall.c b/hw/spapr_hcall.c
index 826ca673fcf711ddf80c3086719666af710b806e..194d9c24b545b63e48b2a690112fe5eaf3d3a2a1 100644 (file)
--- a/hw/spapr_hcall.c
+++ b/hw/spapr_hcall.c
@@ -681,11 +681,6 @@ void spapr_register_hypercall(target_ulong opcode, spapr_hcall_fn fn)
 target_ulong spapr_hypercall(CPUPPCState *env, target_ulong opcode,
                              target_ulong *args)
 {
-    if (msr_pr) {
-        hcall_dprintf("Hypercall made with MSR[PR]=1\n");
-        return H_PRIVILEGE;
-    }
-
     if ((opcode <= MAX_HCALL_OPCODE)
         && ((opcode & 0x3) == 0)) {
         spapr_hcall_fn fn = papr_hypercall_table[opcode / 4];