add launchpad bug reports without comments

1 files changed, 8 insertions, 0 deletions

diff --git a/results/scraper/launchpad-without-comments/1211910 b/results/scraper/launchpad-without-comments/1211910
new file mode 100644
index 000000000..79bf190bf
--- /dev/null
+++ b/results/scraper/launchpad-without-comments/1211910
@@ -0,0 +1,8 @@
+Logical to linear address translation is wrong for 32-bit guests on a 64-bit hypervisor
+
+I run a 64-bit hypervisor in qemu-system-x86_64 (without KVM) and on top of that I have a 32-bit guest. The guest configures the code-segment to have a base of 0x4000_0000 and a limit of 0xFFFF_FFFF with paging disabled. Thus, if a logical address of e.g. 0xC000_0000 is used, it should be translated to 0x0000_0000 (linear and physical), because of the overflow that happens.
+But this does not happen with the described setup. Instead, qemu seems to calculate the logical to linear translation with 64-bit addresses so that no overflow happens. Consequently, the resulting address is 0x1_0000_0000 and this gets written to exitinfo2 in the VMCB structure. This causes trouble for hypervisors that expect the upper 32 bits of exitinfo2 to be 0 for 32-bit guests.
+
+Note also that the exact same setup runs fine on real AMD machines with SVM. That is, the upper 32 bits in exitinfo2 are always 0 because of the overflow.
+
+I've tested that with the latest development version of QEMU (commit 328465fd9f3a628ab320b5959d68d3d49df58fa6).
\ No newline at end of file