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* Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds2017-05-08
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull KVM updates from Paolo Bonzini: "ARM: - HYP mode stub supports kexec/kdump on 32-bit - improved PMU support - virtual interrupt controller performance improvements - support for userspace virtual interrupt controller (slower, but necessary for KVM on the weird Broadcom SoCs used by the Raspberry Pi 3) MIPS: - basic support for hardware virtualization (ImgTec P5600/P6600/I6400 and Cavium Octeon III) PPC: - in-kernel acceleration for VFIO s390: - support for guests without storage keys - adapter interruption suppression x86: - usual range of nVMX improvements, notably nested EPT support for accessed and dirty bits - emulation of CPL3 CPUID faulting generic: - first part of VCPU thread request API - kvm_stat improvements" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (227 commits) kvm: nVMX: Don't validate disabled secondary controls KVM: put back #ifndef CONFIG_S390 around kvm_vcpu_kick Revert "KVM: Support vCPU-based gfn->hva cache" tools/kvm: fix top level makefile KVM: x86: don't hold kvm->lock in KVM_SET_GSI_ROUTING KVM: Documentation: remove VM mmap documentation kvm: nVMX: Remove superfluous VMX instruction fault checks KVM: x86: fix emulation of RSM and IRET instructions KVM: mark requests that need synchronization KVM: return if kvm_vcpu_wake_up() did wake up the VCPU KVM: add explicit barrier to kvm_vcpu_kick KVM: perform a wake_up in kvm_make_all_cpus_request KVM: mark requests that do not need a wakeup KVM: remove #ifndef CONFIG_S390 around kvm_vcpu_wake_up KVM: x86: always use kvm_make_request instead of set_bit KVM: add kvm_{test,clear}_request to replace {test,clear}_bit s390: kvm: Cpu model support for msa6, msa7 and msa8 KVM: x86: remove irq disablement around KVM_SET_CLOCK/KVM_GET_CLOCK kvm: better MWAIT emulation for guests KVM: x86: virtualize cpuid faulting ...
| * KVM: s390: use defines for execution controlsDavid Hildenbrand2017-03-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Let's replace the bitmasks by defines. Reconstructed from code, comments and commit messages. Tried to keep the defines short and map them to feature names. In case they don't completely map to features, keep them in the stye of ICTL defines. This effectively drops all "U" from the existing numbers. I think this should be fine (as similarly done for e.g. ICTL defines). I am not 100% sure about the ECA_MVPGI and ECA_PROTEXCI bits as they are always used in pairs. Signed-off-by: David Hildenbrand <david@redhat.com> Message-Id: <20170313104828.13362-1-david@redhat.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> [some renames, add one missing place]
* | KVM: s390: remove change-recording override supportHeiko Carstens2017-04-03
|/ | | | | | | | | | | | | | | | | | | | | | | | | Change-recording override (CO) was never implemented in any machine. According to the architecture it is unpredictable if a translation-specification exception will be recognized if the bit is set and EDAT1 does not apply. Therefore the easiest solution is to simply ignore the bit. This also fixes commit cd1836f583d7 ("KVM: s390: instruction-execution-protection support"). A guest may enable instruction-execution-protection (IEP) but not EDAT1. In such a case the guest_translate() function (arch/s390/kvm/gaccess.c) will report a specification exception on pages that have the IEP bit set while it should not. It might make sense to add full IEP support to guest_translate() and the GACC_IFETCH case. However, as far as I can tell the GACC_IFETCH case is currently only used after an instruction was executed in order to fetch the failing instruction. So there is no additional problem *currently*. Fixes: cd1836f583d7 ("KVM: s390: instruction-execution-protection support") Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* sched/headers: Prepare to remove the <linux/mm_types.h> dependency from ↵Ingo Molnar2017-03-02
| | | | | | | | | | | | | | | <linux/sched.h> Update code that relied on sched.h including various MM types for them. This will allow us to remove the <linux/mm_types.h> include from <linux/sched.h>. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* KVM: s390: Get rid of ar_tChristian Borntraeger2017-01-30
| | | | | | | | | | | | | | | sparse with __CHECK_ENDIAN__ shows that ar_t was never properly used across KVM on s390. We can now: - fix all places - do not make ar_t special Since ar_t is just used as a register number (no endianness issues for u8), and all other register numbers are also just plain int variables, let's just use u8, which matches the __u8 in the userspace ABI for the memop ioctl. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
* KVM: s390: gaccess: add ESOP2 handlingChristian Borntraeger2017-01-30
| | | | | | | | | | | | | | When we access guest memory and run into a protection exception, we need to pass the exception data to the guest. ESOP2 provides detailed information about all protection exceptions which ESOP1 only partially provided. The gaccess changes make sure, that the guest always gets all available information. Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com> Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: gaccess: simplify translation exception handlingJanosch Frank2016-09-08
| | | | | | | | | | The payload data for protection exceptions is a superset of the payload of other translation exceptions. Let's set the additional flags and use a fall through to minimize code duplication. Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com> Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* s390/mm: support real-space for gmap shadowsDavid Hildenbrand2016-06-20
| | | | | | | | | | | | | | | | | | | | | We can easily support real-space designation just like EDAT1 and EDAT2. So guest2 can provide for guest3 an asce with the real-space control being set. We simply have to allocate the biggest page table possible and fake all levels. There is no protection to consider. If we exceed guest memory, vsie code will inject an addressing exception (via program intercept). In the future, we could limit the fake table level to the gmap page table. As the top level page table can never go away, such gmap shadows will never get unshadowed, we'll have to come up with another way to limit the number of kept gmap shadows. Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* s390/mm: push rte protection down to shadow pteDavid Hildenbrand2016-06-20
| | | | | | | | | Just like we already do with ste protection, let's take rte protection into account. This way, the host pte doesn't have to be mapped writable. Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* s390/mm: support EDAT2 for gmap shadowsDavid Hildenbrand2016-06-20
| | | | | | | | | | | | | | | | | | | | | | | | | If the guest is enabled for EDAT2, we can easily create shadows for guest2 -> guest3 provided tables that make use of EDAT2. If guest2 references a 2GB page, this memory looks consecutive for guest2, but it does not have to be so for us. Therefore we have to create fake segment and page tables. This works just like EDAT1 support, so page tables are removed when the parent table (r3t table entry) is changed. We don't hve to care about: - ACCF-Validity Control in RTTE - Access-Control Bits in RTTE - Fetch-Protection Bit in RTTE - Common-Region Bit in RTTE Just like for EDAT1, all bits might be dropped and there is no guaranteed that they are active. Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* s390/mm: support EDAT1 for gmap shadowsDavid Hildenbrand2016-06-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If the guest is enabled for EDAT1, we can easily create shadows for guest2 -> guest3 provided tables that make use of EDAT1. If guest2 references a 1MB page, this memory looks consecutive for guest2, but it might not be so for us. Therefore we have to create fake page tables. We can easily add that to our existing infrastructure. The invalidation mechanism will make sure that fake page tables are removed when the parent table (sgt table entry) is changed. As EDAT1 also introduced protection on all page table levels, we have to also shadow these correctly. We don't have to care about: - ACCF-Validity Control in STE - Access-Control Bits in STE - Fetch-Protection Bit in STE - Common-Segment Bit in STE As all bits might be dropped and there is no guaranteed that they are active ("unpredictable whether the CPU uses these bits", "may be used"). Without using EDAT1 in the shadow ourselfes (STE-format control == 0), simply shadowing these bits would not be enough. They would be ignored. Please note that we are using the "fake" flag to make this look consistent with further changes (EDAT2, real-space designation support) and don't let the shadow functions handle fc=1 stes. In the future, with huge pages in the host, gmap_shadow_pgt() could simply try to map a huge host page if "fake" is set to one and indicate via return value that no lower fake tables / shadow ptes are required. Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* s390/mm: push ste protection down to shadow pteDavid Hildenbrand2016-06-20
| | | | | | | | | | | | | | | If a guest ste is read-only, it doesn't make sense to force the ptes in as writable in the host. If the source page is read-only in the host, it won't have to be made writable. Please note that if the source page is not available, it will still be faulted in writable. This can be changed internally later on. If ste protection is removed, underlying shadow tables are also removed, therefore this change does not affect the guest. Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* s390/mm: take ipte_lock during shadow faultsDavid Hildenbrand2016-06-20
| | | | | | | | | Let's take the ipte_lock while working on guest 2 provided page table, just like the other gaccess functions. Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* s390/mm: protection exceptions are corrrectly shadowedDavid Hildenbrand2016-06-20
| | | | | | | | | | | | | As gmap shadows contains correct protection permissions, protection exceptons can directly be forwarded to guest 3. If we would encounter a protection exception while faulting, the next guest 3 run will automatically handle that for us. Keep the dat_protection logic in place, as it will be helpful later. Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* s390/mm: take the mmap_sem in kvm_s390_shadow_fault()David Hildenbrand2016-06-20
| | | | | | | | | | Instead of doing it in the caller, let's just take the mmap_sem in kvm_s390_shadow_fault(). By taking it as read, we allow parallel faulting on shadow page tables, gmap shadow code is prepared for that. Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* s390/mm: shadow pages with real guest requested protectionDavid Hildenbrand2016-06-20
| | | | | | | | | | | | | | | | | We really want to avoid manually handling protection for nested virtualization. By shadowing pages with the protection the guest asked us for, the SIE can handle most protection-related actions for us (e.g. special handling for MVPG) and we can directly forward protection exceptions to the guest. PTEs will now always be shadowed with the correct _PAGE_PROTECT flag. Unshadowing will take care of any guest changes to the parent PTE and any host changes to the host PTE. If the host PTE doesn't have the fitting access rights or is not available, we have to fix it up. Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* s390/mm: add kvm shadow fault functionMartin Schwidefsky2016-06-20
| | | | | | | | | | | | | | | | This patch introduces function kvm_s390_shadow_fault() used to resolve a fault on a shadow gmap. This function will do validity checking and build up the shadow page table hierarchy in order to fault in the requested page into the shadow page table structure. If an exception occurs while shadowing, guest 2 has to be notified about it using either an exception or a program interrupt intercept. If concurrent unshadowing occurres, this function will simply return with -EAGAIN and the caller has to retry. Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: gaccess: convert get_vcpu_asce()David Hildenbrand2016-06-10
| | | | | | | Let's use our new function for preparing translation exceptions. Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: gaccess: convert guest_page_range()David Hildenbrand2016-06-10
| | | | | | | | | | | Let's use our new function for preparing translation exceptions. As we will need the correct ar, let's pass that to guest_page_range(). This will also make sure that the guest address is stored in the tec for applicable excptions. Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: gaccess: convert guest_translate_address()David Hildenbrand2016-06-10
| | | | | | | Let's use our new function for preparing translation exceptions. Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: gaccess: convert kvm_s390_check_low_addr_prot_real()David Hildenbrand2016-06-10
| | | | | | | Let's use our new function for preparing translation exceptions. Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: gaccess: function for preparing translation exceptionsDavid Hildenbrand2016-06-10
| | | | | | | | | Let's provide a function trans_exc() that can be used for handling preparation of translation exceptions on a central basis. We will use that function to replace existing code in gaccess. Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: gaccess: store guest address on ALC prot exceptionsDavid Hildenbrand2016-06-10
| | | | | | | | | Let's pass the effective guest address to get_vcpu_asce(), so we can properly set the guest address in case we inject an ALC protection exception. Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: gaccess: implement instruction fetching modeDavid Hildenbrand2016-02-10
| | | | | | | | | | | | | | | When an instruction is to be fetched, special handling applies to secondary-space mode and access-register mode. The instruction is to be fetched from primary space. We can easily support this by selecting the right asce for translation. Access registers will never be used during translation, so don't include them in the interface. As we only want to read from the current PSW address for now, let's also hide that detail. Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: gaccess: introduce access modesDavid Hildenbrand2016-02-10
| | | | | | | | | | We will need special handling when fetching instructions, so let's introduce new guest access modes GACC_FETCH and GACC_STORE instead of a write flag. An additional patch will then introduce GACC_IFETCH. Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: Introduce switching codeEugene (jno) Dvurechenski2015-11-30
| | | | | | | | | | | | | | This patch adds code that performs transparent switch to Extended SCA on addition of 65th VCPU in a VM. Disposal of ESCA is added too. The entier ESCA functionality, however, is still not enabled. The enablement will be provided in a separate patch. This patch also uses read/write lock protection of SCA and its subfields for possible disposal at the BSCA-to-ESCA transition. While only Basic SCA needs such a protection (for the swap), any SCA access is now guarded. Signed-off-by: Eugene (jno) Dvurechenski <jno@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: Generalize access to IPTE controlsEugene (jno) Dvurechenski2015-11-30
| | | | | | | | This patch generalizes access to the IPTE controls, which is a part of SCA. This is to prepare for upcoming introduction of Extended SCA support. Signed-off-by: Eugene (jno) Dvurechenski <jno@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: Add MEMOP ioctls for reading/writing guest memoryThomas Huth2015-03-17
| | | | | | | | | | | | | On s390, we've got to make sure to hold the IPTE lock while accessing logical memory. So let's add an ioctl for reading and writing logical memory to provide this feature for userspace, too. The maximum transfer size of this call is limited to 64kB to prevent that the guest can trigger huge copy_from/to_user transfers. QEMU currently only requests up to one or two pages so far, so 16*4kB seems to be a reasonable limit here. Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: Add access register modeAlexander Yarygin2015-03-17
| | | | | | | | | | | | | Access register mode is one of the modes that control dynamic address translation. In this mode the address space is specified by values of the access registers. The effective address-space-control element is obtained from the result of the access register translation. See the "Access-Register Introduction" section of the chapter 5 "Program Execution" in "Principles of Operations" for more details. Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com> Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: Optimize paths where get_vcpu_asce() is invokedAlexander Yarygin2015-03-17
| | | | | | | | | | | | | During dynamic address translation the get_vcpu_asce() function can be invoked several times. It's ok for usual modes, but will be slow if CPUs are in AR mode. Let's call the get_vcpu_asce() once and pass the result to the called functions. Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com> Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com> Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: Guest's memory access functions get access registersAlexander Yarygin2015-03-17
| | | | | | | | | | | In access register mode, the write_guest() read_guest() and other functions will invoke the access register translation, which requires an ar, designated by one of the instruction fields. Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com> Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: Fix low-address protection for real addressesAlexander Yarygin2015-03-17
| | | | | | | | | | | | | | | | | | The kvm_s390_check_low_addr_protection() function is used only with real addresses. According to the POP (the "Low-Address Protection" paragraph in chapter 3), if the effective address is real or absolute, the low-address protection procedure should raise a PROTECTION exception only when the low-address protection is enabled in the control register 0 and the address is low. This patch removes ASCE checks from the function and renames it to better reflect its behavior. Cc: Thomas Huth <thuth@linux.vnet.ibm.com> Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com> Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com> Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: Fix trivial typo in commentsYannick Guerrini2015-03-06
| | | | | | | | Change 'architecuture' to 'architecture' Signed-off-by: Yannick Guerrini <yguerrini@tomshardware.fr> Message-Id: <1424989004-14412-1-git-send-email-yguerrini@tomshardware.fr> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: use facilities and cpu_id per KVMMichael Mueller2015-02-09
| | | | | | | | | | | The patch introduces facilities and cpu_ids per virtual machine. Different virtual machines may want to expose different facilities and cpu ids to the guest, so let's make them per-vm instead of global. Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* Merge tag 'for-linus' of ↵Linus Torvalds2014-12-20
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux Pull ACCESS_ONCE cleanup preparation from Christian Borntraeger: "kernel: Provide READ_ONCE and ASSIGN_ONCE As discussed on LKML http://marc.info/?i=54611D86.4040306%40de.ibm.com ACCESS_ONCE might fail with specific compilers for non-scalar accesses. Here is a set of patches to tackle that problem. The first patch introduce READ_ONCE and ASSIGN_ONCE. If the data structure is larger than the machine word size memcpy is used and a warning is emitted. The next patches fix up several in-tree users of ACCESS_ONCE on non-scalar types. This does not yet contain a patch that forces ACCESS_ONCE to work only on scalar types. This is targetted for the next merge window as Linux next already contains new offenders regarding ACCESS_ONCE vs. non-scalar types" * tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux: s390/kvm: REPLACE barrier fixup with READ_ONCE arm/spinlock: Replace ACCESS_ONCE with READ_ONCE arm64/spinlock: Replace ACCESS_ONCE READ_ONCE mips/gup: Replace ACCESS_ONCE with READ_ONCE x86/gup: Replace ACCESS_ONCE with READ_ONCE x86/spinlock: Replace ACCESS_ONCE with READ_ONCE mm: replace ACCESS_ONCE with READ_ONCE or barriers kernel: Provide READ_ONCE and ASSIGN_ONCE
| * s390/kvm: REPLACE barrier fixup with READ_ONCEChristian Borntraeger2014-12-18
| | | | | | | | | | | | | | | | | | | | | | | | | | ACCESS_ONCE does not work reliably on non-scalar types. For example gcc 4.6 and 4.7 might remove the volatile tag for such accesses during the SRA (scalar replacement of aggregates) step (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145) Commit 1365039d0cb3 ("KVM: s390: Fix ipte locking") replace ACCESS_ONCE with barriers. Lets use READ_ONCE instead. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* | Merge tag 'kvm-s390-next-20141107' of ↵Paolo Bonzini2014-11-07
|\| | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD KVM: s390: Fixes for kvm/next (3.19) and stable 1. We should flush TLBs for load control instruction emulation (stable) 2. A workaround for a compiler bug that renders ACCESS_ONCE broken (stable) 3. Fix program check handling for load control 4. Documentation Fix
| * KVM: s390: Fix ipte lockingChristian Borntraeger2014-11-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ipte_unlock_siif uses cmpxchg to replace the in-memory data of the ipte lock together with ACCESS_ONCE for the intial read. union ipte_control { unsigned long val; struct { unsigned long k : 1; unsigned long kh : 31; unsigned long kg : 32; }; }; [...] static void ipte_unlock_siif(struct kvm_vcpu *vcpu) { union ipte_control old, new, *ic; ic = &vcpu->kvm->arch.sca->ipte_control; do { new = old = ACCESS_ONCE(*ic); new.kh--; if (!new.kh) new.k = 0; } while (cmpxchg(&ic->val, old.val, new.val) != old.val); if (!new.kh) wake_up(&vcpu->kvm->arch.ipte_wq); } The new value, is loaded twice from memory with gcc 4.7.2 of fedora 18, despite the ACCESS_ONCE: ---> l %r4,0(%r3) <--- load first 32 bit of lock (k and kh) in r4 alfi %r4,2147483647 <--- add -1 to r4 llgtr %r4,%r4 <--- zero out the sign bit of r4 lg %r1,0(%r3) <--- load all 64 bit of lock into new lgr %r2,%r1 <--- load the same into old risbg %r1,%r4,1,31,32 <--- shift and insert r4 into the bits 1-31 of new llihf %r4,2147483647 ngrk %r4,%r1,%r4 jne aa0 <ipte_unlock+0xf8> nihh %r1,32767 lgr %r4,%r2 csg %r4,%r1,0(%r3) cgr %r2,%r4 jne a70 <ipte_unlock+0xc8> If the memory value changes between the first load (l) and the second load (lg) we are broken. If that happens VCPU threads will hang (unkillable) in handle_ipte_interlock. Andreas Krebbel analyzed this and tracked it down to a compiler bug in that version: "while it is not that obvious the C99 standard basically forbids duplicating the memory access also in that case. For an argumentation of a similiar case please see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=22278#c43 For the implementation-defined cases regarding volatile there are some GCC-specific clarifications which can be found here: https://gcc.gnu.org/onlinedocs/gcc/Volatiles.html#Volatiles I've tracked down the problem with a reduced testcase. The problem was that during a tree level optimization (SRA - scalar replacement of aggregates) the volatile marker is lost. And an RTL level optimizer (CSE - common subexpression elimination) then propagated the memory read into its second use introducing another access to the memory location. So indeed Christian's suspicion that the union access has something to do with it is correct (since it triggered the SRA optimization). This issue has been reported and fixed in the GCC 4.8 development cycle: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145" This patch replaces the ACCESS_ONCE scheme with a barrier() based scheme that should work for all supported compilers. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Cc: stable@vger.kernel.org # v3.16+
* | KVM: s390: Make the simple ipte mutex specific to a VM instead of globalThomas Huth2014-10-28
|/ | | | | | | | | | | | The ipte-locking should be done for each VM seperately, not globally. This way we avoid possible congestions when the simple ipte-lock is used and multiple VMs are running. Suggested-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: get rid of constant condition in ipte_unlock_simpleChristian Borntraeger2014-09-10
| | | | | | | | | Due to the earlier check we know that ipte_lock_count must be 0. No need to add a useless if. Let's make clear that we are going to always wakeup when we execute that code. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
* KVM: s390: Enable DAT support for TPROT handlerThomas Huth2014-05-30
| | | | | | | | | | | | The TPROT instruction can be used to check the accessability of storage for any kind of logical addresses. So far, our handler only supported real addresses. This patch now also enables support for addresses that have to be translated via DAT first. And while we're at it, change the code to use the common KVM function gfn_to_hva_prot() to check for the validity and writability of the memory page. Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
* KVM: s390: Add a generic function for translating guest addressesThomas Huth2014-05-30
| | | | | | | | This patch adds a function for translating logical guest addresses into physical guest addresses without touching the memory at the given location. Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
* KVM: s390: Add a function for checking the low-address protectionThomas Huth2014-04-29
| | | | | | | | | | | | The s390 architecture has a special protection mechanism that can be used to prevent write access to the vital data in the low-core memory area. This patch adds a new helper function that can be used to check for such write accesses and in case of protection, it also sets up the exception data accordingly. Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: make use of ipte lockHeiko Carstens2014-04-22
| | | | | | Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
* KVM: s390: add architecture compliant guest access functionsHeiko Carstens2014-04-22
The new guest memory access function write_guest() and read_guest() can be used to access guest memory in an architecture compliant way. These functions will look at the vcpu's PSW and select the correct address space for memory access and also perform correct address wrap around. In case DAT is turned on, page tables will be walked otherwise access will happen to real or absolute memory. Any access exception will be recognized and exception data will be stored in the vcpu's kvm_vcpu_arch.pgm member. Subsequently an exception can be injected if necessary. Missing are: - key protection checks - access register mode support - program event recording support This patch also adds write_guest_real(), read_guest_real(), write_guest_absolute() and read_guest_absolute() guest functions which can be used to access real and absolute storage. These functions currently do not perform any access checks, since there is no use case (yet?). Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
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