All of lore.kernel.org
 help / color / mirror / Atom feed
* [PATCH] target/riscv: fix check of guest pa top bits
@ 2020-04-24 15:09 ` Jose Martins
  0 siblings, 0 replies; 9+ messages in thread
From: Jose Martins @ 2020-04-24 15:09 UTC (permalink / raw)
  To: qemu-riscv; +Cc: alistair.francis, qemu-devel

The spec states that on sv39x4 guest physical  "address bits 63:41
must all be zeros, or else a guest-page-fault exception occurs.".
However, the check performed for these top bits of the virtual address
on the second stage is the same as the one performed for virtual
addresses on the first stage except with the 2-bit extension,
effectively creating the same kind of "hole" in the guest's physical
address space. I believe the following patch fixes this issue:

Signed-off-by: Jose Martins <josemartins90@gmail.com>
---
 target/riscv/cpu_helper.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index d3ba9efb02..da879f5656 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -421,15 +421,21 @@ static int get_physical_address(CPURISCVState
*env, hwaddr *physical,
     int va_bits = PGSHIFT + levels * ptidxbits + widened;
     target_ulong mask, masked_msbs;

-    if (TARGET_LONG_BITS > (va_bits - 1)) {
-        mask = (1L << (TARGET_LONG_BITS - (va_bits - 1))) - 1;
+    if(!first_stage){
+        if ((addr >> va_bits) != 0) {
+            return TRANSLATE_FAIL;
+        }
     } else {
-        mask = 0;
-    }
-    masked_msbs = (addr >> (va_bits - 1)) & mask;
+        if (TARGET_LONG_BITS > (va_bits - 1)) {
+            mask = (1L << (TARGET_LONG_BITS - (va_bits - 1))) - 1;
+        } else {
+            mask = 0;
+        }
+        masked_msbs = (addr >> (va_bits - 1)) & mask;

-    if (masked_msbs != 0 && masked_msbs != mask) {
-        return TRANSLATE_FAIL;
+        if (masked_msbs != 0 && masked_msbs != mask) {
+            return TRANSLATE_FAIL;
+        }
     }

     int ptshift = (levels - 1) * ptidxbits;
-- 
2.17.1

Jose


^ permalink raw reply related	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2020-05-01 19:16 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-04-24 15:09 [PATCH] target/riscv: fix check of guest pa top bits Jose Martins
2020-04-24 15:09 ` Jose Martins
2020-04-30 19:45 ` Alistair Francis
2020-04-30 19:45   ` Alistair Francis
2020-04-30 21:28   ` Alistair Francis
2020-04-30 21:28     ` Alistair Francis
2020-05-01 18:54     ` Jose Martins
2020-05-01 18:54       ` Jose Martins
2020-05-01 19:14       ` Jonathan Behrens

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.