kernel/git/stable/linux-stable.git/arch/s390, branch linux-5.14.y

Revert "sched: Add wrapper for get_wchan() to keep task blocked"

2021-11-18T13:01:34+00:00

This reverts commit e9ede14c116f1a6246eee89d320d60a90a86b5d5 which is commit 42a20f86dc19f9282d974df0ba4d226c865ab9dd upstream. It has been reported to be causing problems, and is being reworked upstream and has been dropped from the current 5.15.y stable queue until it gets resolved. Reported-by: Chris Rankin Reported-by: Thorsten Leemhuis Link: https://lore.kernel.org/r/ed000478-2a60-0066-c337-a04bffc112b1@leemhuis.info Cc: Stephen Rothwell Cc: Peter Zijlstra (Intel) Cc: Kees Cook Cc: Geert Uytterhoeven Cc: Russell King (Oracle) Cc: Mark Rutland Cc: Sasha Levin Signed-off-by: Greg Kroah-Hartman

s390/cpumf: cpum_cf PMU displays invalid value after hotplug remove

2021-11-17T10:04:48+00:00

commit 9d48c7afedf91a02d03295837ec76b2fb5e7d3fe upstream. When a CPU is hotplugged while the perf stat -e cycles command is running, a wrong (very large) value is displayed immediately after the CPU removal: Check the values, shouldn't be too high as in time counts unit events 1.001101919 29261846 cycles 2.002454499 17523405 cycles 3.003659292 24361161 cycles 4.004816983 18446744073638406144 cycles 5.005671647 cycles ... The CPU hotplug off took place after 3 seconds. The issue is the read of the event count value after 4 seconds when the CPU is not available and the read of the counter returns an error. This is treated as a counter value of zero. This results in a very large value (0 - previous_value). Fix this by detecting the hotplugged off CPU and report 0 instead of a very large number. Cc: stable@vger.kernel.org Fixes: a029a4eab39e ("s390/cpumf: Allow concurrent access for CPU Measurement Counter Facility") Reported-by: Sumanth Korikkar Signed-off-by: Thomas Richter Reviewed-by: Sumanth Korikkar Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

KVM: s390: Fix handle_sske page fault handling

2021-11-17T10:04:16+00:00

[ Upstream commit 85f517b29418158d3e6e90c3f0fc01b306d2f1a1 ] If handle_sske cannot set the storage key, because there is no page table entry or no present large page entry, it calls fixup_user_fault. However, currently, if the call succeeds, handle_sske returns -EAGAIN, without having set the storage key. Instead, retry by continue'ing the loop without incrementing the address. The same issue in handle_pfmf was fixed by a11bdb1a6b78 ("KVM: s390: Fix pfmf and conditional skey emulation"). Fixes: bd096f644319 ("KVM: s390: Add skey emulation fault handling") Signed-off-by: Janis Schoetterl-Glausch Reviewed-by: Christian Borntraeger Reviewed-by: Claudio Imbrenda Link: https://lore.kernel.org/r/20211022152648.26536-1-scgl@linux.ibm.com Signed-off-by: Christian Borntraeger Signed-off-by: Sasha Levin

sched: Add wrapper for get_wchan() to keep task blocked

2021-11-17T10:04:16+00:00

[ Upstream commit 42a20f86dc19f9282d974df0ba4d226c865ab9dd ] Having a stable wchan means the process must be blocked and for it to stay that way while performing stack unwinding. Suggested-by: Peter Zijlstra Signed-off-by: Kees Cook Signed-off-by: Peter Zijlstra (Intel) Acked-by: Geert Uytterhoeven Acked-by: Russell King (Oracle) [arm] Tested-by: Mark Rutland [arm64] Link: https://lkml.kernel.org/r/20211008111626.332092234@infradead.org Signed-off-by: Sasha Levin

KVM: s390: pv: avoid stalls for kvm_s390_pv_init_vm

2021-11-17T10:04:14+00:00

[ Upstream commit 1e2aa46de526a5adafe580bca4c25856bb06f09e ] When the system is heavily overcommitted, kvm_s390_pv_init_vm might generate stall notifications. Fix this by using uv_call_sched instead of just uv_call. This is ok because we are not holding spinlocks. Signed-off-by: Claudio Imbrenda Fixes: 214d9bbcd3a672 ("s390/mm: provide memory management functions for protected KVM guests") Reviewed-by: Christian Borntraeger Reviewed-by: Janosch Frank Message-Id: <20210920132502.36111-4-imbrenda@linux.ibm.com> Signed-off-by: Janosch Frank Signed-off-by: Christian Borntraeger Signed-off-by: Sasha Levin

KVM: s390: pv: avoid double free of sida page

2021-11-17T10:04:14+00:00

[ Upstream commit d4074324b07a94a1fca476d452dfbb3a4e7bf656 ] If kvm_s390_pv_destroy_cpu is called more than once, we risk calling free_page on a random page, since the sidad field is aliased with the gbea, which is not guaranteed to be zero. This can happen, for example, if userspace calls the KVM_PV_DISABLE IOCTL, and it fails, and then userspace calls the same IOCTL again. This scenario is only possible if KVM has some serious bug or if the hardware is broken. The solution is to simply return successfully immediately if the vCPU was already non secure. Signed-off-by: Claudio Imbrenda Fixes: 19e1227768863a1469797c13ef8fea1af7beac2c ("KVM: S390: protvirt: Introduce instruction data area bounce buffer") Reviewed-by: Janosch Frank Reviewed-by: Christian Borntraeger Message-Id: <20210920132502.36111-3-imbrenda@linux.ibm.com> Signed-off-by: Janosch Frank Signed-off-by: Christian Borntraeger Signed-off-by: Sasha Levin

s390/uv: fully validate the VMA before calling follow_page()

2021-11-17T10:04:14+00:00

[ Upstream commit 46c22ffd2772201662350bc7b94b9ea9d3ee5ac2 ] We should not walk/touch page tables outside of VMA boundaries when holding only the mmap sem in read mode. Evil user space can modify the VMA layout just before this function runs and e.g., trigger races with page table removal code since commit dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap"). find_vma() does not check if the address is >= the VMA start address; use vma_lookup() instead. Fixes: 214d9bbcd3a6 ("s390/mm: provide memory management functions for protected KVM guests") Signed-off-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Acked-by: Heiko Carstens Reviewed-by: Liam R. Howlett Link: https://lore.kernel.org/r/20210909162248.14969-6-david@redhat.com Signed-off-by: Christian Borntraeger Signed-off-by: Sasha Levin

s390/mm: fix VMA and page table handling code in storage key handling functions

2021-11-17T10:04:14+00:00

[ Upstream commit 949f5c1244ee6c36d2e81c588d1200eaa83a3df6 ] There are multiple things broken about our storage key handling functions: 1. We should not walk/touch page tables outside of VMA boundaries when holding only the mmap sem in read mode. Evil user space can modify the VMA layout just before this function runs and e.g., trigger races with page table removal code since commit dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap"). gfn_to_hva() will only translate using KVM memory regions, but won't validate the VMA. 2. We should not allocate page tables outside of VMA boundaries: if evil user space decides to map hugetlbfs to these ranges, bad things will happen because we suddenly have PTE or PMD page tables where we shouldn't have them. 3. We don't handle large PUDs that might suddenly appeared inside our page table hierarchy. Don't manually allocate page tables, properly validate that we have VMA and bail out on pud_large(). All callers of page table handling functions, except get_guest_storage_key(), call fixup_user_fault() in case they receive an -EFAULT and retry; this will allocate the necessary page tables if required. To keep get_guest_storage_key() working as expected and not requiring kvm_s390_get_skeys() to call fixup_user_fault() distinguish between "there is simply no page table or huge page yet and the key is assumed to be 0" and "this is a fault to be reported". Although commit 637ff9efe5ea ("s390/mm: Add huge pmd storage key handling") introduced most of the affected code, it was actually already broken before when using get_locked_pte() without any VMA checks. Note: Ever since commit 637ff9efe5ea ("s390/mm: Add huge pmd storage key handling") we can no longer set a guest storage key (for example from QEMU during VM live migration) without actually resolving a fault. Although we would have created most page tables, we would choke on the !pmd_present(), requiring a call to fixup_user_fault(). I would have thought that this is problematic in combination with postcopy life migration ... but nobody noticed and this patch doesn't change the situation. So maybe it's just fine. Fixes: 9fcf93b5de06 ("KVM: S390: Create helper function get_guest_storage_key") Fixes: 24d5dd0208ed ("s390/kvm: Provide function for setting the guest storage key") Fixes: a7e19ab55ffd ("KVM: s390: handle missing storage-key facility") Signed-off-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Acked-by: Heiko Carstens Link: https://lore.kernel.org/r/20210909162248.14969-5-david@redhat.com Signed-off-by: Christian Borntraeger Signed-off-by: Sasha Levin

s390/mm: validate VMA in PGSTE manipulation functions

2021-11-17T10:04:14+00:00

[ Upstream commit fe3d10024073f06f04c74b9674bd71ccc1d787cf ] We should not walk/touch page tables outside of VMA boundaries when holding only the mmap sem in read mode. Evil user space can modify the VMA layout just before this function runs and e.g., trigger races with page table removal code since commit dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap"). gfn_to_hva() will only translate using KVM memory regions, but won't validate the VMA. Further, we should not allocate page tables outside of VMA boundaries: if evil user space decides to map hugetlbfs to these ranges, bad things will happen because we suddenly have PTE or PMD page tables where we shouldn't have them. Similarly, we have to check if we suddenly find a hugetlbfs VMA, before calling get_locked_pte(). Fixes: 2d42f9477320 ("s390/kvm: Add PGSTE manipulation functions") Signed-off-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Acked-by: Heiko Carstens Link: https://lore.kernel.org/r/20210909162248.14969-4-david@redhat.com Signed-off-by: Christian Borntraeger Signed-off-by: Sasha Levin

s390/gmap: don't unconditionally call pte_unmap_unlock() in __gmap_zap()

2021-11-17T10:04:14+00:00

[ Upstream commit b159f94c86b43cf7e73e654bc527255b1f4eafc4 ] ... otherwise we will try unlocking a spinlock that was never locked via a garbage pointer. At the time we reach this code path, we usually successfully looked up a PGSTE already; however, evil user space could have manipulated the VMA layout in the meantime and triggered removal of the page table. Fixes: 1e133ab296f3 ("s390/mm: split arch/s390/mm/pgtable.c") Signed-off-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Acked-by: Heiko Carstens Link: https://lore.kernel.org/r/20210909162248.14969-3-david@redhat.com Signed-off-by: Christian Borntraeger Signed-off-by: Sasha Levin