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KVM/arm64 fixes for 6.3, part #2

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Fixes for a rather interesting set of bugs relating to the MMU:
 
  - Read the MMU notifier seq before dropping the mmap lock to guard
    against reading a potentially stale VMA
 
  - Disable interrupts when walking user page tables to protect against
    the page table being freed
 
  - Read the MTE permissions for the VMA within the mmap lock critical
    section, avoiding the use of a potentally stale VMA pointer
 
 Additionally, some fixes targeting the vPMU:
 
  - Return the sum of the current perf event value and PMC snapshot for
    reads from userspace
 
  - Don't save the value of guest writes to PMCR_EL0.{C,P}, which could
    otherwise lead to userspace erroneously resetting the vPMU during VM
    save/restore
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Merge tag 'kvmarm-fixes-6.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 6.3, part #2

Fixes for a rather interesting set of bugs relating to the MMU:

 - Read the MMU notifier seq before dropping the mmap lock to guard
   against reading a potentially stale VMA

 - Disable interrupts when walking user page tables to protect against
   the page table being freed

 - Read the MTE permissions for the VMA within the mmap lock critical
   section, avoiding the use of a potentally stale VMA pointer

Additionally, some fixes targeting the vPMU:

 - Return the sum of the current perf event value and PMC snapshot for
   reads from userspace

 - Don't save the value of guest writes to PMCR_EL0.{C,P}, which could
   otherwise lead to userspace erroneously resetting the vPMU during VM
   save/restore
This commit is contained in:
Paolo Bonzini 2023-03-27 10:03:16 -04:00
commit 8607daa214
3 changed files with 85 additions and 38 deletions
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