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2017-04-27KVM: x86: fix emulation of RSM and IRET instructionsLadi Prosek1-7/+9
On AMD, the effect of set_nmi_mask called by emulate_iret_real and em_rsm on hflags is reverted later on in x86_emulate_instruction where hflags are overwritten with ctxt->emul_flags (the kvm_set_hflags call). This manifests as a hang when rebooting Windows VMs with QEMU, OVMF, and >1 vcpu. Instead of trying to merge ctxt->emul_flags into vcpu->arch.hflags after an instruction is emulated, this commit deletes emul_flags altogether and makes the emulator access vcpu->arch.hflags using two new accessors. This way all changes, on the emulator side as well as in functions called from the emulator and accessing vcpu state with emul_to_vcpu, are preserved. More details on the bug and its manifestation with Windows and OVMF: It's a KVM bug in the interaction between SMI/SMM and NMI, specific to AMD. I believe that the SMM part explains why we started seeing this only with OVMF. KVM masks and unmasks NMI when entering and leaving SMM. When KVM emulates the RSM instruction in em_rsm, the set_nmi_mask call doesn't stick because later on in x86_emulate_instruction we overwrite arch.hflags with ctxt->emul_flags, effectively reverting the effect of the set_nmi_mask call. The AMD-specific hflag of interest here is HF_NMI_MASK. When rebooting the system, Windows sends an NMI IPI to all but the current cpu to shut them down. Only after all of them are parked in HLT will the initiating cpu finish the restart. If NMI is masked, other cpus never get the memo and the initiating cpu spins forever, waiting for hal!HalpInterruptProcessorsStarted to drop. That's the symptom we observe. Fixes: a584539b24b8 ("KVM: x86: pass the whole hflags field to emulator and back") Signed-off-by: Ladi Prosek <lprosek@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-04-21KVM: x86: virtualize cpuid faultingKyle Huey1-0/+7
Hardware support for faulting on the cpuid instruction is not required to emulate it, because cpuid triggers a VM exit anyways. KVM handles the relevant MSRs (MSR_PLATFORM_INFO and MSR_MISC_FEATURES_ENABLE) and upon a cpuid-induced VM exit checks the cpuid faulting state and the CPL. kvm_require_cpl is even kind enough to inject the GP fault for us. Signed-off-by: Kyle Huey <khuey@kylehuey.com> Reviewed-by: David Matlack <dmatlack@google.com> [Return "1" from kvm_emulate_cpuid, it's not void. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-01-17Merge branch 'x86/cpufeature' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into nextRadim Krčmář1-14/+56
For AVX512_VPOPCNTDQ.
2017-01-12KVM: x86: fix emulation of "MOV SS, null selector"Paolo Bonzini1-10/+38
This is CVE-2017-2583. On Intel this causes a failed vmentry because SS's type is neither 3 nor 7 (even though the manual says this check is only done for usable SS, and the dmesg splat says that SS is unusable!). On AMD it's worse: svm.c is confused and sets CPL to 0 in the vmcb. The fix fabricates a data segment descriptor when SS is set to a null selector, so that CPL and SS.DPL are set correctly in the VMCS/vmcb. Furthermore, only allow setting SS to a NULL selector if SS.RPL < 3; this in turn ensures CPL < 3 because RPL must be equal to CPL. Thanks to Andy Lutomirski and Willy Tarreau for help in analyzing the bug and deciphering the manuals. Reported-by: Xiaohan Zhang <zhangxiaohan1@huawei.com> Fixes: 79d5b4c3cd809c770d4bf9812635647016c56011 Cc: stable@nongnu.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-01-12KVM: x86: Introduce segmented_write_stdSteve Rutherford1-4/+18
Introduces segemented_write_std. Switches from emulated reads/writes to standard read/writes in fxsave, fxrstor, sgdt, and sidt. This fixes CVE-2017-2584, a longstanding kernel memory leak. Since commit 283c95d0e389 ("KVM: x86: emulate FXSAVE and FXRSTOR", 2016-11-09), which is luckily not yet in any final release, this would also be an exploitable kernel memory *write*! Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: stable@vger.kernel.org Fixes: 96051572c819194c37a8367624b285be10297eca Fixes: 283c95d0e3891b64087706b344a4b545d04a6e62 Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Steve Rutherford <srutherford@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-01-09kvm: svm: Use the hardware provided GPA instead of page walkTom Lendacky1-4/+16
When a guest causes a NPF which requires emulation, KVM sometimes walks the guest page tables to translate the GVA to a GPA. This is unnecessary most of the time on AMD hardware since the hardware provides the GPA in EXITINFO2. The only exception cases involve string operations involving rep or operations that use two memory locations. With rep, the GPA will only be the value of the initial NPF and with dual memory locations we won't know which memory address was translated into EXITINFO2. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Reviewed-by: Borislav Petkov <bp@suse.de> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-12-13Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds1-27/+173
Pull KVM updates from Paolo Bonzini: "Small release, the most interesting stuff is x86 nested virt improvements. x86: - userspace can now hide nested VMX features from guests - nested VMX can now run Hyper-V in a guest - support for AVX512_4VNNIW and AVX512_FMAPS in KVM - infrastructure support for virtual Intel GPUs. PPC: - support for KVM guests on POWER9 - improved support for interrupt polling - optimizations and cleanups. s390: - two small optimizations, more stuff is in flight and will be in 4.11. ARM: - support for the GICv3 ITS on 32bit platforms" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (94 commits) arm64: KVM: pmu: Reset PMSELR_EL0.SEL to a sane value before entering the guest KVM: arm/arm64: timer: Check for properly initialized timer on init KVM: arm/arm64: vgic-v2: Limit ITARGETSR bits to number of VCPUs KVM: x86: Handle the kthread worker using the new API KVM: nVMX: invvpid handling improvements KVM: nVMX: check host CR3 on vmentry and vmexit KVM: nVMX: introduce nested_vmx_load_cr3 and call it on vmentry KVM: nVMX: propagate errors from prepare_vmcs02 KVM: nVMX: fix CR3 load if L2 uses PAE paging and EPT KVM: nVMX: load GUEST_EFER after GUEST_CR0 during emulated VM-entry KVM: nVMX: generate MSR_IA32_CR{0,4}_FIXED1 from guest CPUID KVM: nVMX: fix checks on CR{0,4} during virtual VMX operation KVM: nVMX: support restore of VMX capability MSRs KVM: nVMX: generate non-true VMX MSRs based on true versions KVM: x86: Do not clear RFLAGS.TF when a singlestep trap occurs. KVM: x86: Add kvm_skip_emulated_instruction and use it. KVM: VMX: Move skip_emulated_instruction out of nested_vmx_check_vmcs12 KVM: VMX: Reorder some skip_emulated_instruction calls KVM: x86: Add a return value to kvm_emulate_cpuid KVM: PPC: Book3S: Move prototypes for KVM functions into kvm_ppc.h ...
2016-11-24KVM: x86: drop error recovery in em_jmp_far and em_ret_farRadim Krčmář1-25/+11
em_jmp_far and em_ret_far assumed that setting IP can only fail in 64 bit mode, but syzkaller proved otherwise (and SDM agrees). Code segment was restored upon failure, but it was left uninitialized outside of long mode, which could lead to a leak of host kernel stack. We could have fixed that by always saving and restoring the CS, but we take a simpler approach and just break any guest that manages to fail as the error recovery is error-prone and modern CPUs don't need emulator for this. Found by syzkaller: WARNING: CPU: 2 PID: 3668 at arch/x86/kvm/emulate.c:2217 em_ret_far+0x428/0x480 Kernel panic - not syncing: panic_on_warn set ... CPU: 2 PID: 3668 Comm: syz-executor Not tainted 4.9.0-rc4+ #49 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 [...] Call Trace: [...] __dump_stack lib/dump_stack.c:15 [...] dump_stack+0xb3/0x118 lib/dump_stack.c:51 [...] panic+0x1b7/0x3a3 kernel/panic.c:179 [...] __warn+0x1c4/0x1e0 kernel/panic.c:542 [...] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585 [...] em_ret_far+0x428/0x480 arch/x86/kvm/emulate.c:2217 [...] em_ret_far_imm+0x17/0x70 arch/x86/kvm/emulate.c:2227 [...] x86_emulate_insn+0x87a/0x3730 arch/x86/kvm/emulate.c:5294 [...] x86_emulate_instruction+0x520/0x1ba0 arch/x86/kvm/x86.c:5545 [...] emulate_instruction arch/x86/include/asm/kvm_host.h:1116 [...] complete_emulated_io arch/x86/kvm/x86.c:6870 [...] complete_emulated_mmio+0x4e9/0x710 arch/x86/kvm/x86.c:6934 [...] kvm_arch_vcpu_ioctl_run+0x3b7a/0x5a90 arch/x86/kvm/x86.c:6978 [...] kvm_vcpu_ioctl+0x61e/0xdd0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2557 [...] vfs_ioctl fs/ioctl.c:43 [...] do_vfs_ioctl+0x18c/0x1040 fs/ioctl.c:679 [...] SYSC_ioctl fs/ioctl.c:694 [...] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [...] entry_SYSCALL_64_fastpath+0x1f/0xc2 Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: stable@vger.kernel.org Fixes: d1442d85cc30 ("KVM: x86: Handle errors when RIP is set during far jumps") Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2016-11-16KVM: x86: emulate FXSAVE and FXRSTORRadim Krčmář1-1/+128
Internal errors were reported on 16 bit fxsave and fxrstor with ipxe. Old Intels don't have unrestricted_guest, so we have to emulate them. The patch takes advantage of the hardware implementation. AMD and Intel differ in saving and restoring other fields in first 32 bytes. A test wrote 0xff to the fxsave area, 0 to upper bits of MCSXR in the fxsave area, executed fxrstor, rewrote the fxsave area to 0xee, and executed fxsave: Intel (Nehalem): 7f 1f 7f 7f ff 00 ff 07 ff ff ff ff ff ff 00 00 ff ff ff ff ff ff 00 00 ff ff 00 00 ff ff 00 00 Intel (Haswell -- deprecated FPU CS and FPU DS): 7f 1f 7f 7f ff 00 ff 07 ff ff ff ff 00 00 00 00 ff ff ff ff 00 00 00 00 ff ff 00 00 ff ff 00 00 AMD (Opteron 2300-series): 7f 1f 7f 7f ff 00 ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ff ff 00 00 ff ff 02 00 fxsave/fxrstor will only be emulated on early Intels, so KVM can't do much to improve the situation. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2016-11-16KVM: x86: add asm_safe wrapperRadim Krčmář1-11/+23
Move the existing exception handling for inline assembly into a macro and switch its return values to X86EMUL type. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-11-16KVM: x86: save one bit in ctxt->dRadim Krčmář1-10/+13
Alignments are exclusive, so 5 modes can be expressed in 3 bits. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-11-16KVM: x86: add Align16 instruction flagRadim Krčmář1-8/+12
Needed for FXSAVE and FXRSTOR. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-11-02kvm: x86: Check memopp before dereference (CVE-2016-8630)Owen Hofmann1-1/+1
Commit 41061cdb98 ("KVM: emulate: do not initialize memopp") removes a check for non-NULL under incorrect assumptions. An undefined instruction with a ModR/M byte with Mod=0 and R/M-5 (e.g. 0xc7 0x15) will attempt to dereference a null pointer here. Fixes: 41061cdb98a0bec464278b4db8e894a3121671f5 Message-Id: <1477592752-126650-2-git-send-email-osh@google.com> Signed-off-by: Owen Hofmann <osh@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-07-14x86/kvm: Audit and remove any unnecessary uses of module.hPaul Gortmaker1-1/+0
Historically a lot of these existed because we did not have a distinction between what was modular code and what was providing support to modules via EXPORT_SYMBOL and friends. That changed when we forked out support for the latter into the export.h file. This means we should be able to reduce the usage of module.h in code that is obj-y Makefile or bool Kconfig. In the case of kvm where it is modular, we can extend that to also include files that are building basic support functionality but not related to loading or registering the final module; such files also have no need whatsoever for module.h The advantage in removing such instances is that module.h itself sources about 15 other headers; adding significantly to what we feed cpp, and it can obscure what headers we are effectively using. Since module.h was the source for init.h (for __init) and for export.h (for EXPORT_SYMBOL) we consider each instance for the presence of either and replace as needed. Several instances got replaced with moduleparam.h since that was really all that was required for those particular files. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kvm@vger.kernel.org Link: http://lkml.kernel.org/r/20160714001901.31603-8-paul.gortmaker@windriver.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-10x86/kvm: Add stack frame dependency to fastop() inline asmJosh Poimboeuf1-1/+5
The kbuild test robot reported this objtool warning [1]: arch/x86/kvm/emulate.o: warning: objtool: fastop()+0x69: call without frame pointer save/setup The issue seems to be caused by CONFIG_PROFILE_ALL_BRANCHES. With that option, for some reason gcc decides not to create a stack frame in fastop() before doing the inline asm call, which can result in a bad stack trace. Force a stack frame to be created if CONFIG_FRAME_POINTER is enabled by listing the stack pointer as an output operand for the inline asm statement. This change has no effect for !CONFIG_PROFILE_ALL_BRANCHES. [1] https://lists.01.org/pipermail/kbuild-all/2016-March/018249.html Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-03-20Merge branch 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds1-9/+22
Pull 'objtool' stack frame validation from Ingo Molnar: "This tree adds a new kernel build-time object file validation feature (ONFIG_STACK_VALIDATION=y): kernel stack frame correctness validation. It was written by and is maintained by Josh Poimboeuf. The motivation: there's a category of hard to find kernel bugs, most of them in assembly code (but also occasionally in C code), that degrades the quality of kernel stack dumps/backtraces. These bugs are hard to detect at the source code level. Such bugs result in incorrect/incomplete backtraces most of time - but can also in some rare cases result in crashes or other undefined behavior. The build time correctness checking is done via the new 'objtool' user-space utility that was written for this purpose and which is hosted in the kernel repository in tools/objtool/. The tool's (very simple) UI and source code design is shaped after Git and perf and shares quite a bit of infrastructure with tools/perf (which tooling infrastructure sharing effort got merged via perf and is already upstream). Objtool follows the well-known kernel coding style. Objtool does not try to check .c or .S files, it instead analyzes the resulting .o generated machine code from first principles: it decodes the instruction stream and interprets it. (Right now objtool supports the x86-64 architecture.) From tools/objtool/Documentation/stack-validation.txt: "The kernel CONFIG_STACK_VALIDATION option enables a host tool named objtool which runs at compile time. It has a "check" subcommand which analyzes every .o file and ensures the validity of its stack metadata. It enforces a set of rules on asm code and C inline assembly code so that stack traces can be reliable. Currently it only checks frame pointer usage, but there are plans to add CFI validation for C files and CFI generation for asm files. For each function, it recursively follows all possible code paths and validates the correct frame pointer state at each instruction. It also follows code paths involving special sections, like .altinstructions, __jump_table, and __ex_table, which can add alternative execution paths to a given instruction (or set of instructions). Similarly, it knows how to follow switch statements, for which gcc sometimes uses jump tables." When this new kernel option is enabled (it's disabled by default), the tool, if it finds any suspicious assembly code pattern, outputs warnings in compiler warning format: warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch warning: objtool: cik_tiling_mode_table_init()+0x6ce: call without frame pointer save/setup warning: objtool:__schedule()+0x3c0: duplicate frame pointer save warning: objtool:__schedule()+0x3fd: sibling call from callable instruction with changed frame pointer ... so that scripts that pick up compiler warnings will notice them. All known warnings triggered by the tool are fixed by the tree, most of the commits in fact prepare the kernel to be warning-free. Most of them are bugfixes or cleanups that stand on their own, but there are also some annotations of 'special' stack frames for justified cases such entries to JIT-ed code (BPF) or really special boot time code. There are two other long-term motivations behind this tool as well: - To improve the quality and reliability of kernel stack frames, so that they can be used for optimized live patching. - To create independent infrastructure to check the correctness of CFI stack frames at build time. CFI debuginfo is notoriously unreliable and we cannot use it in the kernel as-is without extra checking done both on the kernel side and on the build side. The quality of kernel stack frames matters to debuggability as well, so IMO we can merge this without having to consider the live patching or CFI debuginfo angle" * 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits) objtool: Only print one warning per function objtool: Add several performance improvements tools: Copy hashtable.h into tools directory objtool: Fix false positive warnings for functions with multiple switch statements objtool: Rename some variables and functions objtool: Remove superflous INIT_LIST_HEAD objtool: Add helper macros for traversing instructions objtool: Fix false positive warnings related to sibling calls objtool: Compile with debugging symbols objtool: Detect infinite recursion objtool: Prevent infinite recursion in noreturn detection objtool: Detect and warn if libelf is missing and don't break the build tools: Support relative directory path for 'O=' objtool: Support CROSS_COMPILE x86/asm/decoder: Use explicitly signed chars objtool: Enable stack metadata validation on 64-bit x86 objtool: Add CONFIG_STACK_VALIDATION option objtool: Add tool to perform compile-time stack metadata validation x86/kprobes: Mark kretprobe_trampoline() stack frame as non-standard sched: Always inline context_switch() ...
2016-02-24KVM: x86: fix conversion of addresses to linear in 32-bit protected modePaolo Bonzini1-2/+2
Commit e8dd2d2d641c ("Silence compiler warning in arch/x86/kvm/emulate.c", 2015-09-06) broke boot of the Hurd. The bug is that the "default:" case actually could modify "la", but after the patch this change is not reflected in *linear. The bug is visible whenever a non-zero segment base causes the linear address to wrap around the 4GB mark. Fixes: e8dd2d2d641cb2724ee10e76c0ad02e04289c017 Cc: stable@vger.kernel.org Reported-by: Aurelien Jarno <aurelien@aurel32.net> Tested-by: Aurelien Jarno <aurelien@aurel32.net> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-24x86/kvm: Make test_cc() always inlineJosh Poimboeuf1-1/+1
With some configs (including allyesconfig), gcc doesn't inline test_cc(). When that happens, test_cc() doesn't create a stack frame before inserting the inline asm call instruction. This breaks frame pointer convention if CONFIG_FRAME_POINTER is enabled and can result in a bad stack trace. Force it to always be inlined so that its containing function's stack frame can be used. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Gleb Natapov <gleb@kernel.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kvm@vger.kernel.org Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/20160122161612.GE20502@treble.redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-24x86/kvm: Set ELF function type for fastop functionsJosh Poimboeuf1-8/+21
The callable functions created with the FOP* and FASTOP* macros are missing ELF function annotations, which confuses tools like stacktool. Properly annotate them. This adds some additional labels to the assembly, but the generated binary code is unchanged (with the exception of instructions which have embedded references to __LINE__). Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Gleb Natapov <gleb@kernel.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kvm@vger.kernel.org Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/e399651c89ace54906c203c0557f66ed6ea3ce8d.1453405861.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-04KVM: x86: allow RSM from 64-bit modePaolo Bonzini1-5/+25
The SDM says that exiting system management mode from 64-bit mode is invalid, but that would be too good to be true. But actually, most of the code is already there to support exiting from compat mode (EFER.LME=1, EFER.LMA=0). Getting all the way from 64-bit mode to real mode only requires clearing CS.L and CR4.PCIDE. Cc: stable@vger.kernel.org Fixes: 660a5d517aaab9187f93854425c4c63f4a09195c Tested-by: Laszlo Ersek <lersek@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-11-04KVM: x86: handle SMBASE as physical address in RSMRadim Krčmář1-4/+3
GET_SMSTATE depends on real mode to ensure that smbase+offset is treated as a physical address, which has already caused a bug after shuffling the code. Enforce physical addressing. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Reported-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Laszlo Ersek <lersek@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-10-14KVM: x86: fix RSM into 64-bit protected modePaolo Bonzini1-3/+7
In order to get into 64-bit protected mode, you need to enable paging while EFER.LMA=1. For this to work, CS.L must be 0. Currently, we load the segments before CR0 and CR4, which means that if RSM returns into 64-bit protected mode CS.L is already 1 and everything breaks. Luckily, CS.L=0 is always the case when executing RSM, because it is forbidden to execute RSM from 64-bit protected mode. Hence it is enough to load CR0 and CR4 first, and only then the segments. Fixes: 660a5d517aaab9187f93854425c4c63f4a09195c Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-09-06Silence compiler warning in arch/x86/kvm/emulate.cValdis Kletnieks1-1/+1
Compiler warning: CC [M] arch/x86/kvm/emulate.o arch/x86/kvm/emulate.c: In function "__do_insn_fetch_bytes": arch/x86/kvm/emulate.c:814:9: warning: "linear" may be used uninitialized in this function [-Wmaybe-uninitialized] GCC is smart enough to realize that the inlined __linearize may return before setting the value of linear, but not smart enough to realize the same X86EMU_CONTINUE blocks actual use of the value. However, the value of 'linear' can only be set to one value, so hoisting the one line of code upwards makes GCC happy with the code. Reported-by: Aruna Hewapathirane <aruna.hewapathirane@gmail.com> Tested-by: Aruna Hewapathirane <aruna.hewapathirane@gmail.com> Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-06-04KVM: x86: save/load state on SMM switchPaolo Bonzini1-1/+247
The big ugly one. This patch adds support for switching in and out of system management mode, respectively upon receiving KVM_REQ_SMI and upon executing a RSM instruction. Both 32- and 64-bit formats are supported for the SMM state save area. Reviewed-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-06-04KVM: x86: stubs for SMM supportPaolo Bonzini1-1/+9
This patch adds the interface between x86.c and the emulator: the SMBASE register, a new emulator flag, the RSM instruction. It also adds a new request bit that will be used by the KVM_SMI ioctl. Reviewed-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-06-04KVM: x86: pass the whole hflags field to emulator and backPaolo Bonzini1-3/+3
The hflags field will contain information about system management mode and will be useful for the emulator. Pass the entire field rather than just the guest-mode information. Reviewed-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-05-19KVM: x86: Fix zero iterations REP-stringNadav Amit1-0/+25
When a REP-string is executed in 64-bit mode with an address-size prefix, ECX/EDI/ESI are used as counter and pointers. When ECX is initially zero, Intel CPUs clear the high 32-bits of RCX, and recent Intel CPUs update the high bits of the pointers in MOVS/STOS. This behavior is specific to Intel according to few experiments. As one may guess, this is an undocumented behavior. Yet, it is observable in the guest, since at least VMX traps REP-INS/OUTS even when ECX=0. Note that VMware appears to get it right. The behavior can be observed using the following code: #include <stdio.h> #define LOW_MASK (0xffffffff00000000ull) #define ALL_MASK (0xffffffffffffffffull) #define TEST(opcode) \ do { \ asm volatile(".byte 0xf2 \n\t .byte 0x67 \n\t .byte " opcode "\n\t" \ : "=S"(s), "=c"(c), "=D"(d) \ : "S"(ALL_MASK), "c"(LOW_MASK), "D"(ALL_MASK)); \ printf("opcode %s rcx=%llx rsi=%llx rdi=%llx\n", \ opcode, c, s, d); \ } while(0) void main() { unsigned long long s, d, c; iopl(3); TEST("0x6c"); TEST("0x6d"); TEST("0x6e"); TEST("0x6f"); TEST("0xa4"); TEST("0xa5"); TEST("0xa6"); TEST("0xa7"); TEST("0xaa"); TEST("0xab"); TEST("0xae"); TEST("0xaf"); } Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-05-19KVM: x86: Fix update RCX/RDI/RSI on REP-stringNadav Amit1-6/+2
When REP-string instruction is preceded with an address-size prefix, ECX/EDI/ESI are used as the operation counter and pointers. When they are updated, the high 32-bits of RCX/RDI/RSI are cleared, similarly to the way they are updated on every 32-bit register operation. Fix it. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-05-19KVM: x86: Fix DR7 mask on task-switch while debuggingNadav Amit1-1/+5
If the host sets hardware breakpoints to debug the guest, and a task-switch occurs in the guest, the architectural DR7 will not be updated. The effective DR7 would be updated instead. This fix puts the DR7 update during task-switch emulation, so it now uses the standard DR setting mechanism instead of the one that was previously used. As a bonus, the update of DR7 will now be effective for AMD as well. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-05-08KVM: x86: Call-far should not be emulated as stack opNadav Amit1-1/+1
Far call in 64-bit has a 32-bit operand size. Remove the marking of this operation as Stack so it can be emulated correctly in 64-bit. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-04-08kvm: x86: fix x86 eflags fixed bitWanpeng Li1-3/+3
Guest can't be booted w/ ept=0, there is a message dumped as below: If you're running a guest on an Intel machine without unrestricted mode support, the failure can be most likely due to the guest entering an invalid state for Intel VT. For example, the guest maybe running in big real mode which is not supported on less recent Intel processors. EAX=00000011 EBX=f000d2f6 ECX=00006cac EDX=000f8956 ESI=bffbdf62 EDI=00000000 EBP=00006c68 ESP=00006c68 EIP=0000d187 EFL=00000004 [-----P-] CPL=0 II=0 A20=1 SMM=0 HLT=0 ES =e000 000e0000 ffffffff 00809300 DPL=0 DS16 [-WA] CS =f000 000f0000 ffffffff 00809b00 DPL=0 CS16 [-RA] SS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA] DS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA] FS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA] GS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA] LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy GDT= 000f6a80 00000037 IDT= 000f6abe 00000000 CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000 DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 DR6=00000000ffff0ff0 DR7=0000000000000400 EFER=0000000000000000 Code=01 1e b8 6a 2e 0f 01 16 74 6a 0f 20 c0 66 83 c8 01 0f 22 c0 <66> ea 8f d1 0f 00 08 00 b8 10 00 00 00 8e d8 8e c0 8e d0 8e e0 8e e8 89 c8 ff e2 89 c1 b8X X86 eflags bit 1 is fixed set, which means that 1 << 1 is set instead of 1, this patch fix it. Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com> Message-Id: <1428473294-6633-1-git-send-email-wanpeng.li@linux.intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: remove useless check of "ret" variable prior to returning the same valueEugene Korenevsky1-3/+1
A trivial code cleanup. This `if` is redundant. Signed-off-by: Eugene Korenevsky <ekorenevsky@gmail.com> Message-Id: <20150328222717.GA6508@gnote> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: x86: Remove redundant definitionsNadav Amit1-3/+3
Some constants are redfined in emulate.c. Avoid it. s/SELECTOR_RPL_MASK/SEGMENT_RPL_MASK s/SELECTOR_TI_MASK/SEGMENT_TI_MASK No functional change. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Message-Id: <1427635984-8113-3-git-send-email-namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: x86: removing redundant eflags bits definitionsNadav Amit1-59/+46
The eflags are redefined (using other defines) in emulate.c. Use the definition from processor-flags.h as some mess already started. No functional change. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Message-Id: <1427635984-8113-2-git-send-email-namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: x86: BSF and BSR emulation change register unnecassarilyNadav Amit1-1/+18
If the source of BSF and BSR is zero, the destination register should not change. That is how real hardware behaves. If we set the destination even with the same value that we had before, we may clear bits [63:32] unnecassarily. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Message-Id: <1427719163-5429-4-git-send-email-namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: x86: POPA emulation may not clear bits [63:32]Nadav Amit1-16/+23
POPA should assign the values to the registers as usual registers are assigned. In other words, 32-bits register assignments should clear bits [63:32] of the register. Split the code of register assignments that will be used by future changes as well. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Message-Id: <1427719163-5429-3-git-send-email-namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-30KVM: x86: CMOV emulation on legacy mode is wrongNadav Amit1-2/+1
On legacy mode CMOV emulation should still clear bits [63:32] even if the assignment is not done. The previous fix 140bad89fd ("KVM: x86: emulation of dword cmov on long-mode should clear [63:32]") was incomplete. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Message-Id: <1427719163-5429-2-git-send-email-namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-03-13KVM: x86: Fix re-execution of patched vmmcallJan Kiszka1-14/+3
For a very long time (since 2b3d2a20), the path handling a vmmcall instruction of the guest on an Intel host only applied the patch but no longer handled the hypercall. The reverse case, vmcall on AMD hosts, is fine. As both em_vmcall and em_vmmcall actually have to do the same, we can fix the issue by consolidating both into the same handler. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2015-02-23KVM: emulate: fix CMPXCHG8B on 32-bit hostsPaolo Bonzini1-1/+2
This has been broken for a long time: it broke first in 2.6.35, then was almost fixed in 2.6.36 but this one-liner slipped through the cracks. The bug shows up as an infinite loop in Windows 7 (and newer) boot on 32-bit hosts without EPT. Windows uses CMPXCHG8B to write to page tables, which causes a page fault if running without EPT; the emulator is then called from kvm_mmu_page_fault. The loop then happens if the higher 4 bytes are not 0; the common case for this is that the NX bit (bit 63) is 1. Fixes: 6550e1f165f384f3a46b60a1be9aba4bc3c2adad Fixes: 16518d5ada690643453eb0aef3cc7841d3623c2d Cc: stable@vger.kernel.org # 2.6.35+ Reported-by: Erik Rull <erik.rull@rdsoftware.de> Tested-by: Erik Rull <erik.rull@rdsoftware.de> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-02-13Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds1-74/+156
Pull KVM update from Paolo Bonzini: "Fairly small update, but there are some interesting new features. Common: Optional support for adding a small amount of polling on each HLT instruction executed in the guest (or equivalent for other architectures). This can improve latency up to 50% on some scenarios (e.g. O_DSYNC writes or TCP_RR netperf tests). This also has to be enabled manually for now, but the plan is to auto-tune this in the future. ARM/ARM64: The highlights are support for GICv3 emulation and dirty page tracking s390: Several optimizations and bugfixes. Also a first: a feature exposed by KVM (UUID and long guest name in /proc/sysinfo) before it is available in IBM's hypervisor! :) MIPS: Bugfixes. x86: Support for PML (page modification logging, a new feature in Broadwell Xeons that speeds up dirty page tracking), nested virtualization improvements (nested APICv---a nice optimization), usual round of emulation fixes. There is also a new option to reduce latency of the TSC deadline timer in the guest; this needs to be tuned manually. Some commits are common between this pull and Catalin's; I see you have already included his tree. Powerpc: Nothing yet. The KVM/PPC changes will come in through the PPC maintainers, because I haven't received them yet and I might end up being offline for some part of next week" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (130 commits) KVM: ia64: drop kvm.h from installed user headers KVM: x86: fix build with !CONFIG_SMP KVM: x86: emulate: correct page fault error code for NoWrite instructions KVM: Disable compat ioctl for s390 KVM: s390: add cpu model support KVM: s390: use facilities and cpu_id per KVM KVM: s390/CPACF: Choose crypto control block format s390/kernel: Update /proc/sysinfo file with Extended Name and UUID KVM: s390: reenable LPP facility KVM: s390: floating irqs: fix user triggerable endless loop kvm: add halt_poll_ns module parameter kvm: remove KVM_MMIO_SIZE KVM: MIPS: Don't leak FPU/DSP to guest KVM: MIPS: Disable HTW while in guest KVM: nVMX: Enable nested posted interrupt processing KVM: nVMX: Enable nested virtual interrupt delivery KVM: nVMX: Enable nested apic register virtualization KVM: nVMX: Make nested control MSRs per-cpu KVM: nVMX: Enable nested virtualize x2apic mode KVM: nVMX: Prepare for using hardware MSR bitmap ...
2015-02-09KVM: x86: emulate: correct page fault error code for NoWrite instructionsPaolo Bonzini1-1/+2
NoWrite instructions (e.g. cmp or test) never set the "write access" bit in the error code, even if one of the operands is treated as a destination. Fixes: c205fb7d7d4f81e46fc577b707ceb9e356af1456 Cc: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-01-26KVM: x86: Emulation of call may use incorrect stack sizeNadav Amit1-7/+18
On long-mode, when far call that changes cs.l takes place, the stack size is determined by the new mode. For instance, if we go from 32-bit mode to 64-bit mode, the stack-size if 64. KVM uses the old stack size. Fix it. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-01-26KVM: x86: 32-bit wraparound read/write not emulated correctlyNadav Amit1-3/+7
If we got a wraparound of 32-bit operand, and the limit is 0xffffffff, read and writes should be successful. It just needs to be done in two segments. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-01-26KVM: x86: Fix defines in emulator.cNadav Amit1-1/+1
Unnecassary define was left after commit 7d882ffa81d5 ("KVM: x86: Revert NoBigReal patch in the emulator"). Commit 39f062ff51b2 ("KVM: x86: Generate #UD when memory operand is required") was missing undef. Fix it. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-01-26KVM: x86: ARPL emulation can cause spurious exceptionsNadav Amit1-6/+26
ARPL and MOVSXD are encoded the same and their execution depends on the execution mode. The operand sizes of each instruction are different. Currently, ARPL is detected too late, after the decoding was already done, and therefore may result in spurious exception (instead of failed emulation). Introduce a group to the emulator to handle instructions according to execution mode (32/64 bits). Note: in order not to make changes that may affect performance, the new ModeDual can only be applied to instructions with ModRM. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-01-26KVM: x86: IRET emulation does not clear NMI maskingNadav Amit1-0/+1
The IRET instruction should clear NMI masking, but the current implementation does not do so. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-01-26KVM: x86: Wrong operand size for far retNadav Amit1-2/+2
Indeed, Intel SDM specifically states that for the RET instruction "In 64-bit mode, the default operation size of this instruction is the stack-address size, i.e. 64 bits." However, experiments show this is not the case. Here is for example objdump of small 64-bit asm: 4004f1: ca 14 00 lret $0x14 4004f4: 48 cb lretq 4004f6: 48 ca 14 00 lretq $0x14 Therefore, remove the Stack flag from far-ret instructions. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-01-26KVM: x86: Dirty the dest op page on cmpxchg emulationNadav Amit1-4/+7
Intel SDM says for CMPXCHG: "To simplify the interface to the processor’s bus, the destination operand receives a write cycle without regard to the result of the comparison.". This means the destination page should be dirtied. Fix it to by writing back the original value if cmpxchg failed. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-01-23KVM: x86: SYSENTER emulation is brokenNadav Amit1-19/+8
SYSENTER emulation is broken in several ways: 1. It misses the case of 16-bit code segments completely (CVE-2015-0239). 2. MSR_IA32_SYSENTER_CS is checked in 64-bit mode incorrectly (bits 0 and 1 can still be set without causing #GP). 3. MSR_IA32_SYSENTER_EIP and MSR_IA32_SYSENTER_ESP are not masked in legacy-mode. 4. There is some unneeded code. Fix it. Cc: stable@vger.linux.org Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-01-23KVM: x86: Fix of previously incomplete fix for CVE-2014-8480Nadav Amit1-2/+2
STR and SLDT with rip-relative operand can cause a host kernel oops. Mark them as DstMem as well. Cc: stable@vger.linux.org Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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