[Qemu-devel] [PATCH 2/3] spapr/xive: fix EQ page addresses above 64GB

["Cédric Le Goater" <clg@kaod.org>]

The high order bits of the address of the OS event queue is stored in
bits [4-31] of word2 of the XIVE END internal structures and the low
order bits in word3. This structure is using Big Endian ordering and
computing the value requires some simple arithmetic which happens to
be wrong. The mask removing bits [0-3] of word2 is applied to the
wrong value and the resulting address is bogus when above 64GB.

Guests with more than 64GB of RAM will allocate pages for the OS event
queues which will reside above the 64GB limit. In this case, the XIVE
device model will wake up the CPUs in case of a notification, such as
IPIs, but the update of the event queue will be written at the wrong
place in memory. The result is uncertain as the guest memory is
trashed and IPI are not delivered.

Introduce a helper xive_end_qaddr() to compute this value correctly in
all places where it is used.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 include/hw/ppc/xive_regs.h | 6 ++++++
 hw/intc/spapr_xive.c       | 3 +--
 hw/intc/xive.c             | 9 +++------
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/include/hw/ppc/xive_regs.h b/include/hw/ppc/xive_regs.h
index bf36678a242c..1a8c5b5e64f0 100644
--- a/include/hw/ppc/xive_regs.h
+++ b/include/hw/ppc/xive_regs.h
@@ -208,6 +208,12 @@ typedef struct XiveEND {
 #define xive_end_is_backlog(end)  (be32_to_cpu((end)->w0) & END_W0_BACKLOG)
 #define xive_end_is_escalate(end) (be32_to_cpu((end)->w0) & END_W0_ESCALATE_CTL)
 
+static inline uint64_t xive_end_qaddr(XiveEND *end)
+{
+    return ((uint64_t) be32_to_cpu(end->w2) & 0x0fffffff) << 32 |
+        be32_to_cpu(end->w3);
+}
+
 /* Notification Virtual Target (NVT) */
 typedef struct XiveNVT {
         uint32_t        w0;
diff --git a/hw/intc/spapr_xive.c b/hw/intc/spapr_xive.c
index 666e24e9b447..810435c30cc7 100644
--- a/hw/intc/spapr_xive.c
+++ b/hw/intc/spapr_xive.c
@@ -1150,8 +1150,7 @@ static target_ulong h_int_get_queue_config(PowerPCCPU *cpu,
     }
 
     if (xive_end_is_enqueue(end)) {
-        args[1] = (uint64_t) be32_to_cpu(end->w2 & 0x0fffffff) << 32
-            | be32_to_cpu(end->w3);
+        args[1] = xive_end_qaddr(end);
         args[2] = xive_get_field32(END_W0_QSIZE, end->w0) + 12;
     } else {
         args[1] = 0;
diff --git a/hw/intc/xive.c b/hw/intc/xive.c
index a0b87001da25..dcf2fcd10893 100644
--- a/hw/intc/xive.c
+++ b/hw/intc/xive.c
@@ -1042,8 +1042,7 @@ static const TypeInfo xive_source_info = {
 
 void xive_end_queue_pic_print_info(XiveEND *end, uint32_t width, Monitor *mon)
 {
-    uint64_t qaddr_base = (uint64_t) be32_to_cpu(end->w2 & 0x0fffffff) << 32
-        | be32_to_cpu(end->w3);
+    uint64_t qaddr_base = xive_end_qaddr(end);
     uint32_t qsize = xive_get_field32(END_W0_QSIZE, end->w0);
     uint32_t qindex = xive_get_field32(END_W1_PAGE_OFF, end->w1);
     uint32_t qentries = 1 << (qsize + 10);
@@ -1072,8 +1071,7 @@ void xive_end_queue_pic_print_info(XiveEND *end, uint32_t width, Monitor *mon)
 
 void xive_end_pic_print_info(XiveEND *end, uint32_t end_idx, Monitor *mon)
 {
-    uint64_t qaddr_base = (uint64_t) be32_to_cpu(end->w2 & 0x0fffffff) << 32
-        | be32_to_cpu(end->w3);
+    uint64_t qaddr_base = xive_end_qaddr(end);
     uint32_t qindex = xive_get_field32(END_W1_PAGE_OFF, end->w1);
     uint32_t qgen = xive_get_field32(END_W1_GENERATION, end->w1);
     uint32_t qsize = xive_get_field32(END_W0_QSIZE, end->w0);
@@ -1101,8 +1099,7 @@ void xive_end_pic_print_info(XiveEND *end, uint32_t end_idx, Monitor *mon)
 
 static void xive_end_enqueue(XiveEND *end, uint32_t data)
 {
-    uint64_t qaddr_base = (uint64_t) be32_to_cpu(end->w2 & 0x0fffffff) << 32
-        | be32_to_cpu(end->w3);
+    uint64_t qaddr_base = xive_end_qaddr(end);
     uint32_t qsize = xive_get_field32(END_W0_QSIZE, end->w0);
     uint32_t qindex = xive_get_field32(END_W1_PAGE_OFF, end->w1);
     uint32_t qgen = xive_get_field32(END_W1_GENERATION, end->w1);
-- 
2.20.1