When the 'int N' instruction is executed in protected mode, the
pseudocode in the architecture manual specifies that we need to check:
* vector number within IDT limits
* selected IDT descriptor is a valid type (interrupt, trap or task gate)
* if this was a software interrupt then gate DPL < CPL
The way we had structured the code meant that the privilege check for
software interrupts ended up not in the code path taken for task gate
handling, because all of the task gate handling code was in the 'case 5'
of the switch which was checking "is this descriptor a valid type".
Move the task gate handling code out of that switch (so that it is now
purely doing the "valid type?" check) and below the software interrupt
privilege check.
The effect of this missing check was that in a guest userspace binary
executing 'int 8' would cause a guest kernel panic rather than the
userspace binary being handed a SEGV.
This is essentially the same bug fixed in VirtualBox in 2012:
https://www.halfdog.net/Security/2012/VirtualBoxSoftwareInterrupt0x8GuestCrash/
Note that for QEMU this is not a security issue because it is only
present when using TCG.
Backports 3df1a3d070575419859cbbab1083fafa7ec2669a
Per the SDM, when returning to outer privilege level, for segment
registers (ES, FS, GS, and DS) if the check fails, the segment
selector becomes null, but QEMU clears the base/limit/flags as well
as nullifying the segment selector, which should be a spec violation.
Real hardware seems to be compliant with the spec, at least on one
Coffee Lake board I tested.
Backports c2ba0515f2df58a661fcb5d6485139877d92ab1b
There is no "version 2" of the "Lesser" General Public License.
It is either "GPL version 2.0" or "Lesser GPL version 2.1".
This patch replaces all occurrences of "Lesser GPL version 2" with
"Lesser GPL version 2.1" in comment section.
Backport d9ff33ada7f32ca59f99b270a2d0eb223b3c9c8f
Cleanup in the boilerplate that each target must define.
Replace x86_env_get_cpu with env_archcpu. The combination
CPU(x86_env_get_cpu) should have used ENV_GET_CPU to begin;
use env_cpu now.
Backports commit 6aa9e42f27331be34e06d4d66f92f2272868f96a from qemu
Use inline functions rather than macros for cpu_ld/st accessors
for the *-user configurations, as we already do for softmmu.
This has a two advantages:
* we can actually typecheck our arguments
* we don't need to leak the _raw macros everywhere
Since the _kernel functions were only used by target-i386/seg_helper.c,
put the definitions for them in that file too. (It already has the
similar template include code to define them for the softmmu case,
so it makes sense to have it deal with defining them for user-only.)
Backports commit 9220fe54c679d145232a28df6255e166ebf91bab from qemu
Fix the SYSCALL instruction in 64-bit (long mode). The RF flag
should be cleared in R11 as well as in the RFLAGS. Intel
and AMD CPUs behave same. AMD has this documented in the
APM vol 3.
Backports commit 1a1435dd61e28c1e3b70971107d72a7d05b28d03 from qemu
This flag will be used for KVM's nested VMX migration; the HF_GUEST_MASK name
is already used in KVM, adopt it in QEMU as well.
Backports commit f8dc4c645ec2956a6cd97e0ca0fdd4753181f735 from qemu
Interrupt handling depends on various flags in env->hflags or env->hflags2,
and the exact detail were not exactly replicated between x86_cpu_has_work
and x86_cpu_exec_interrupt. Create a new function that extracts the
highest-priority non-masked interrupt, and use it in both functions.
Backports commit 92d5f1a4147c3722b5e9a8bcfb7dc261b7a8b855 from qemu
The current implementation has three bugs,
* segment limits are not enforced in protected mode if the L bit is set
in the target segment descriptor
* segment limits are not enforced in compatibility mode (ljmp to 32-bit
code segment in long mode)
* #GP(new_cs) is generated rather than #GP(0)
Now the segment limits are enforced if we're not in long mode OR the
target code segment doesn't have the L bit set.
Backports commit db7196db5d5d932f388643baae6835f8dcda6921 from qemu
Currently call gates are always treated as 32-bit gates. In IA-32e mode
(either compatibility or 64-bit submode), system segment descriptors are
always 64-bit. Treating them as 32-bit has the expected unfortunate
effect: only the lower 32 bits of the offset are loaded, the stack
pointer is truncated, a bad new stack pointer is loaded from the TSS (if
switching privilege levels), etc.
This change adds support for 64-bit call gate to the lcall and ljmp
instructions. Additionally, there should be a check for non-canonical
stack pointers, but I've omitted that since there doesn't seem to be
checks for non-canonical addresses in this code elsewhere.
I've left the raise_exception_err_ra lines unwapped at 80 columns to
match the style in the rest of the file.
Backports commit 0aca060526d3ff9632aaed66e8611814580c13de from qemu
Check for SVM interception prior to injecting an NMI. Tested via the
Jailhouse hypervisor.
Backports commit 02f7fd25a446a220905c2e5cb0fc3655d7f63b29 from qemu
Move the handling of conforming code segments before the handling
of stack switch.
Because dpl == cpl after the new "if", it's now unnecessary to check
the C bit when testing dpl < cpl. Furthermore, dpl > cpl is checked
slightly above the modified code, so the final "else" is unreachable
and we can remove it.
Backports commit 1110bfe6f5600017258fa6578f9c17ec25b32277 from qemu
In do_interrupt64(), when interrupt stack table(ist) is enabled
and the the target code segment is conforming(e2 & DESC_C_MASK), the
old implementation always set new CPL to 0, and SS.RPL to 0.
This is incorrect for when CPL3 code access a CPL0 conforming code
segment, the CPL should remain unchanged. Otherwise higher privileged
code can be compromised.
The patch fix this for always set dpl = cpl when the target code segment
is conforming, and modify the last parameter `flags`, which contains
correct new CPL, in cpu_x86_load_seg_cache().
Backports commit e95e9b88ba5f4a6c17f4d0c3a3a6bf3f648bb328 from qemu
Paths through the softmmu code during code generation now need to be audited
to check for double locking of tb_lock. In particular, VMEXIT can take tb_lock
through cpu_vmexit -> cpu_x86_update_cr4 -> tlb_flush.
To avoid this, split VMEXIT delivery in two parts, similar to what is done with
exceptions. cpu_vmexit only records the VMEXIT exit code and information, and
cc->do_interrupt can then deliver it when it is safe to take the lock.
Backports commit 10cde894b63146139f981857e4eedf756fa53dcb from qemu
We've currently got 18 architectures in QEMU, and thus 18 target-xxx
folders in the root folder of the QEMU source tree. More architectures
(e.g. RISC-V, AVR) are likely to be included soon, too, so the main
folder of the QEMU sources slowly gets quite overcrowded with the
target-xxx folders.
To disburden the main folder a little bit, let's move the target-xxx
folders into a dedicated target/ folder, so that target-xxx/ simply
becomes target/xxx/ instead.
Backports commit fcf5ef2ab52c621a4617ebbef36bf43b4003f4c0 from qemu
2018-03-01 22:50:58 -05:00
Renamed from qemu/target-i386/seg_helper.c (Browse further)
