On 2/13/24 09:39, Nicholas Piggin wrote:
The move to decodetree flipped the inequality test for the VEC / VSX
MSR facility check.

This caused application crashes under Linux, where these facility
unavailable interrupts are used for lazy-switching of VEC/VSX register
sets. Getting the incorrect interrupt would result in wrong registers
being loaded, potentially overwriting live values and/or exposing
stale ones.

Cc: qemu-sta...@nongnu.org
Reported-by: Joel Stanley <j...@jms.id.au>
Fixes: 70426b5bb738 ("target/ppc: moved stxvx and lxvx from legacy to 
decodtree")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1769
Tested-by: Harsh Prateek Bora <hars...@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npig...@gmail.com>

Reviewed-by: Cédric Le Goater <c...@kaod.org>
Tested-by: Cédric Le Goater <c...@kaod.org>

with a RHEL9 image.

Thanks,

C.


---
  target/ppc/translate/vsx-impl.c.inc | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/ppc/translate/vsx-impl.c.inc 
b/target/ppc/translate/vsx-impl.c.inc
index 6db87ab336..0266f09119 100644
--- a/target/ppc/translate/vsx-impl.c.inc
+++ b/target/ppc/translate/vsx-impl.c.inc
@@ -2268,7 +2268,7 @@ static bool do_lstxv(DisasContext *ctx, int ra, TCGv 
displ,
static bool do_lstxv_D(DisasContext *ctx, arg_D *a, bool store, bool paired)
  {
-    if (paired || a->rt >= 32) {
+    if (paired || a->rt < 32) {
          REQUIRE_VSX(ctx);
      } else {
          REQUIRE_VECTOR(ctx);


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