[PATCH v2 1/1] i386/monitor: Fix page table walking issue for LA57 enabled guest

[Yuan Yao <yuan.yao@intel.com>]

Inverse the condition checking to PG_PRESENT_MASK when walk LA57
guest's pdpe/pde for "info mem" command.

The current condition checking:
if (PG_PRESENT_MASK is set)
    Skip low level page table.
else
    Try to walk low level page table.

This is wrong because PG_PRESENT_MASK is set means the pdpe/pde is
present so we should continue walking the low level page table it
points to. This issue leads to no mapping information is collected for
LA57 guest when run the command.

v2:
1. Fix Typo (Zhang Chen <chen.zhang@intel.com> and Markus Armbruster
<armbru@redhat.com>).
2. Rewrite commit message (Markus Armbruster <armbru@redhat.com>).
3. Add Fixes tag (Markus Armbruster <armbru@redhat.com>).

Fixes: 6c7c3c21f9 ("x86: implement la57 paging mode")
Signed-off-by: Yuan Yao <yuan.yao@intel.com>
Reviewed-by: Zhang Chen <chen.zhang@intel.com>
---
 target/i386/monitor.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/target/i386/monitor.c b/target/i386/monitor.c
index 8e4b4d600c..3339550bbe 100644
--- a/target/i386/monitor.c
+++ b/target/i386/monitor.c
@@ -489,7 +489,7 @@ static void mem_info_la57(Monitor *mon, CPUArchState *env)
                 cpu_physical_memory_read(pdp_addr + l2 * 8, &pdpe, 8);
                 pdpe = le64_to_cpu(pdpe);
                 end = (l0 << 48) + (l1 << 39) + (l2 << 30);
-                if (pdpe & PG_PRESENT_MASK) {
+                if (!(pdpe & PG_PRESENT_MASK)) {
                     prot = 0;
                     mem_print(mon, env, &start, &last_prot, end, prot);
                     continue;
@@ -508,7 +508,7 @@ static void mem_info_la57(Monitor *mon, CPUArchState *env)
                     cpu_physical_memory_read(pd_addr + l3 * 8, &pde, 8);
                     pde = le64_to_cpu(pde);
                     end = (l0 << 48) + (l1 << 39) + (l2 << 30) + (l3 << 21);
-                    if (pde & PG_PRESENT_MASK) {
+                    if (!(pde & PG_PRESENT_MASK)) {
                         prot = 0;
                         mem_print(mon, env, &start, &last_prot, end, prot);
                         continue;
-- 
2.27.0