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Diffstat (limited to 'results/classifier/zero-shot/108/other/1211910')
| -rw-r--r-- | results/classifier/zero-shot/108/other/1211910 | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/results/classifier/zero-shot/108/other/1211910 b/results/classifier/zero-shot/108/other/1211910 new file mode 100644 index 000000000..93f1e470b --- /dev/null +++ b/results/classifier/zero-shot/108/other/1211910 @@ -0,0 +1,28 @@ +graphic: 0.888 +performance: 0.828 +device: 0.775 +semantic: 0.642 +other: 0.624 +permissions: 0.542 +network: 0.533 +vnc: 0.528 +socket: 0.489 +debug: 0.405 +PID: 0.379 +boot: 0.349 +files: 0.340 +KVM: 0.035 + +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). + +Triaging old bug tickets... can you still reproduce this issue with the latest version of QEMU? Or could we close this ticket nowadays? + +[Expired for QEMU because there has been no activity for 60 days.] + |