kernel.git/arch/s390/kvm, branch linux-5.4.y

KVM: s390: Don't use %pK through tracepoints

2025-05-02T05:39:29Z

[ Upstream commit 6c9567e0850be2f0f94ab64fa6512413fd1a1eb1 ] Restricted pointers ("%pK") are not meant to be used through TP_format(). It can unintentionally expose security sensitive, raw pointer values. Use regular pointer formatting instead. Link: https://lore.kernel.org/lkml/20250113171731-dc10e3c1-da64-4af0-b767-7c7070468023@linutronix.de/ Signed-off-by: Thomas Weißschuh Reviewed-by: Michael Mueller Link: https://lore.kernel.org/r/20250217-restricted-pointers-s390-v1-1-0e4ace75d8aa@linutronix.de Signed-off-by: Janosch Frank Message-ID: <20250217-restricted-pointers-s390-v1-1-0e4ace75d8aa@linutronix.de> Signed-off-by: Sasha Levin

KVM: s390: vsie: fix some corner-cases when grabbing vsie pages

2025-03-13T11:43:07Z

commit 5f230f41fdd9e799f43a699348dc572bca7159aa upstream. We try to reuse the same vsie page when re-executing the vsie with a given SCB address. The result is that we use the same shadow SCB -- residing in the vsie page -- and can avoid flushing the TLB when re-running the vsie on a CPU. So, when we allocate a fresh vsie page, or when we reuse a vsie page for a different SCB address -- reusing the shadow SCB in different context -- we set ihcpu=0xffff to trigger the flush. However, after we looked up the SCB address in the radix tree, but before we grabbed the vsie page by raising the refcount to 2, someone could reuse the vsie page for a different SCB address, adjusting page->index and the radix tree. In that case, we would be reusing the vsie page with a wrong page->index. Another corner case is that we might set the SCB address for a vsie page, but fail the insertion into the radix tree. Whoever would reuse that page would remove the corresponding radix tree entry -- which might now be a valid entry pointing at another page, resulting in the wrong vsie page getting removed from the radix tree. Let's handle such races better, by validating that the SCB address of a vsie page didn't change after we grabbed it (not reuse for a different SCB; the alternative would be performing another tree lookup), and by setting the SCB address to invalid until the insertion in the tree succeeded (SCB addresses are aligned to 512, so ULONG_MAX is invalid). These scenarios are rare, the effects a bit unclear, and these issues were only found by code inspection. Let's CC stable to be safe. Fixes: a3508fbe9dc6 ("KVM: s390: vsie: initial support for nested virtualization") Cc: stable@vger.kernel.org Signed-off-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Reviewed-by: Christoph Schlameuss Tested-by: Christoph Schlameuss Message-ID: <20250107154344.1003072-2-david@redhat.com> Signed-off-by: Claudio Imbrenda Signed-off-by: Greg Kroah-Hartman

KVM: s390: gaccess: Check if guest address is in memslot

2024-11-08T15:20:50Z

[ Upstream commit e8061f06185be0a06a73760d6526b8b0feadfe52 ] Previously, access_guest_page() did not check whether the given guest address is inside of a memslot. This is not a problem, since kvm_write_guest_page/kvm_read_guest_page return -EFAULT in this case. However, -EFAULT is also returned when copy_to/from_user fails. When emulating a guest instruction, the address being outside a memslot usually means that an addressing exception should be injected into the guest. Failure in copy_to/from_user however indicates that something is wrong in userspace and hence should be handled there. To be able to distinguish these two cases, return PGM_ADDRESSING in access_guest_page() when the guest address is outside guest memory. In access_guest_real(), populate vcpu->arch.pgm.code such that kvm_s390_inject_prog_cond() can be used in the caller for injecting into the guest (if applicable). Since this adds a new return value to access_guest_page(), we need to make sure that other callers are not confused by the new positive return value. There are the following users of access_guest_page(): - access_guest_with_key() does the checking itself (in guest_range_to_gpas()), so this case should never happen. Even if, the handling is set up properly. - access_guest_real() just passes the return code to its callers, which are: - read_guest_real() - see below - write_guest_real() - see below There are the following users of read_guest_real(): - ar_translation() in gaccess.c which already returns PGM_* - setup_apcb10(), setup_apcb00(), setup_apcb11() in vsie.c which always return -EFAULT on read_guest_read() nonzero return - no change - shadow_crycb(), handle_stfle() always present this as validity, this could be handled better but doesn't change current behaviour - no change There are the following users of write_guest_real(): - kvm_s390_store_status_unloaded() always returns -EFAULT on write_guest_real() failure. Fixes: 2293897805c2 ("KVM: s390: add architecture compliant guest access functions") Cc: stable@vger.kernel.org Signed-off-by: Nico Boehr Reviewed-by: Heiko Carstens Link: https://lore.kernel.org/r/20240917151904.74314-2-nrb@linux.ibm.com Acked-by: Janosch Frank Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin

KVM: s390: gaccess: Cleanup access to guest pages

2024-11-08T15:20:50Z

[ Upstream commit bad13799e0305deb258372b7298a86be4c78aaba ] Introduce a helper function for guest frame access. Signed-off-by: Janis Schoetterl-Glausch Reviewed-by: Janosch Frank Reviewed-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Message-Id: <20211126164549.7046-4-scgl@linux.ibm.com> Signed-off-by: Janosch Frank Stable-dep-of: e8061f06185b ("KVM: s390: gaccess: Check if guest address is in memslot") Signed-off-by: Sasha Levin

KVM: s390: gaccess: Refactor access address range check

2024-11-08T15:20:50Z

[ Upstream commit 7faa543df19bf62d4583a64d3902705747f2ad29 ] Do not round down the first address to the page boundary, just translate it normally, which gives the value we care about in the first place. Given this, translating a single address is just the special case of translating a range spanning a single page. Make the output optional, so the function can be used to just check a range. Signed-off-by: Janis Schoetterl-Glausch Reviewed-by: Janosch Frank Reviewed-by: Claudio Imbrenda Message-Id: <20211126164549.7046-3-scgl@linux.ibm.com> Signed-off-by: Janosch Frank Stable-dep-of: e8061f06185b ("KVM: s390: gaccess: Check if guest address is in memslot") Signed-off-by: Sasha Levin

KVM: s390: gaccess: Refactor gpa and length calculation

2024-11-08T15:20:50Z

[ Upstream commit 416e7f0c9d613bf84e182eba9547ae8f9f5bfa4c ] Improve readability by renaming the length variable and not calculating the offset manually. Signed-off-by: Janis Schoetterl-Glausch Reviewed-by: Janosch Frank Reviewed-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Message-Id: <20211126164549.7046-2-scgl@linux.ibm.com> Signed-off-by: Janosch Frank Stable-dep-of: e8061f06185b ("KVM: s390: gaccess: Check if guest address is in memslot") Signed-off-by: Sasha Levin

KVM: s390: Change virtual to physical address access in diag 0x258 handler

2024-11-08T15:20:48Z

commit cad4b3d4ab1f062708fff33f44d246853f51e966 upstream. The parameters for the diag 0x258 are real addresses, not virtual, but KVM was using them as virtual addresses. This only happened to work, since the Linux kernel as a guest used to have a 1:1 mapping for physical vs virtual addresses. Fix KVM so that it correctly uses the addresses as real addresses. Cc: stable@vger.kernel.org Fixes: 8ae04b8f500b ("KVM: s390: Guest's memory access functions get access registers") Suggested-by: Vasily Gorbik Signed-off-by: Michael Mueller Signed-off-by: Nico Boehr Reviewed-by: Christian Borntraeger Reviewed-by: Heiko Carstens Link: https://lore.kernel.org/r/20240917151904.74314-3-nrb@linux.ibm.com Acked-by: Janosch Frank Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman

KVM: s390: fix setting of fpc register

2024-02-23T07:24:56Z

[ Upstream commit b988b1bb0053c0dcd26187d29ef07566a565cf55 ] kvm_arch_vcpu_ioctl_set_fpu() allows to set the floating point control (fpc) register of a guest cpu. The new value is tested for validity by temporarily loading it into the fpc register. This may lead to corruption of the fpc register of the host process: if an interrupt happens while the value is temporarily loaded into the fpc register, and within interrupt context floating point or vector registers are used, the current fp/vx registers are saved with save_fpu_regs() assuming they belong to user space and will be loaded into fp/vx registers when returning to user space. test_fp_ctl() restores the original user space / host process fpc register value, however it will be discarded, when returning to user space. In result the host process will incorrectly continue to run with the value that was supposed to be used for a guest cpu. Fix this by simply removing the test. There is another test right before the SIE context is entered which will handles invalid values. This results in a change of behaviour: invalid values will now be accepted instead of that the ioctl fails with -EINVAL. This seems to be acceptable, given that this interface is most likely not used anymore, and this is in addition the same behaviour implemented with the memory mapped interface (replace invalid values with zero) - see sync_regs() in kvm-s390.c. Reviewed-by: Christian Borntraeger Reviewed-by: Claudio Imbrenda Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev Signed-off-by: Sasha Levin

KVM: s390: fix sthyi error handling

2023-08-11T09:53:55Z

[ Upstream commit 0c02cc576eac161601927b41634f80bfd55bfa9e ] Commit 9fb6c9b3fea1 ("s390/sthyi: add cache to store hypervisor info") added cache handling for store hypervisor info. This also changed the possible return code for sthyi_fill(). Instead of only returning a condition code like the sthyi instruction would do, it can now also return a negative error value (-ENOMEM). handle_styhi() was not changed accordingly. In case of an error, the negative error value would incorrectly injected into the guest PSW. Add proper error handling to prevent this, and update the comment which describes the possible return values of sthyi_fill(). Fixes: 9fb6c9b3fea1 ("s390/sthyi: add cache to store hypervisor info") Reviewed-by: Christian Borntraeger Link: https://lore.kernel.org/r/20230727182939.2050744-1-hca@linux.ibm.com Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin

KVM: s390: vsie: fix the length of APCB bitmap

2023-07-27T06:37:22Z

[ Upstream commit 246be7d2720ea9a795b576067ecc5e5c7a1e7848 ] bit_and() uses the count of bits as the woking length. Fix the previous implementation and effectively use the right bitmap size. Fixes: 19fd83a64718 ("KVM: s390: vsie: allow CRYCB FORMAT-1") Fixes: 56019f9aca22 ("KVM: s390: vsie: Allow CRYCB FORMAT-2") Signed-off-by: Pierre Morel Reviewed-by: Janosch Frank Link: https://lore.kernel.org/kvm/20230511094719.9691-1-pmorel@linux.ibm.com/ Signed-off-by: Janosch Frank Signed-off-by: Sasha Levin