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| author |   Reiji Watanabe <reijiw@google.com> | 2022-09-16 18:05:57 -0700 |
|---|---|---|
| committer |   Marc Zyngier <maz@kernel.org> | 2022-09-19 10:48:53 +0100 |
| commit | 34fbdee086cfcc20fe889d2b83afddfbe2ac3096 (patch) | |
| tree | d1b4c26f8487bde763a69da0c50f9dd9fc645910 /arch/arm64/include/asm/kvm_host.h | |
| parent | Linux 6.0-rc3 (diff) | |
| download | linux-dev-34fbdee086cfcc20fe889d2b83afddfbe2ac3096.tar.xz linux-dev-34fbdee086cfcc20fe889d2b83afddfbe2ac3096.zip | |
KVM: arm64: Preserve PSTATE.SS for the guest while single-step is enabled
Preserve the PSTATE.SS value for the guest while userspace enables
single-step (i.e. while KVM manipulates the PSTATE.SS) for the vCPU.
Currently, while userspace enables single-step for the vCPU
(with KVM_GUESTDBG_SINGLESTEP), KVM sets PSTATE.SS to 1 on every
guest entry, not saving its original value.
When userspace disables single-step, KVM doesn't restore the original
value for the subsequent guest entry (use the current value instead).
Exception return instructions copy PSTATE.SS from SPSR_ELx.SS
only in certain cases when single-step is enabled (and set it to 0
in other cases). So, the value matters only when the guest enables
single-step (and when the guest's Software step state isn't affected
by single-step enabled by userspace, practically), though.
Fix this by preserving the original PSTATE.SS value while userspace
enables single-step, and restoring the value once it is disabled.
This fix modifies the behavior of GET_ONE_REG/SET_ONE_REG for the
PSTATE.SS while single-step is enabled by userspace.
Presently, GET_ONE_REG/SET_ONE_REG gets/sets the current PSTATE.SS
value, which KVM will override on the next guest entry (i.e. the
value userspace gets/sets is not used for the next guest entry).
With this patch, GET_ONE_REG/SET_ONE_REG will get/set the guest's
preserved value, which KVM will preserve and try to restore after
single-step is disabled.
Fixes: 337b99bf7edf ("KVM: arm64: guest debug, add support for single-step")
Signed-off-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220917010600.532642-2-reijiw@google.com
Diffstat (limited to 'arch/arm64/include/asm/kvm_host.h')
| -rw-r--r-- | arch/arm64/include/asm/kvm_host.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index e9c9388ccc02..ccf8a144f009 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -393,6 +393,7 @@ struct kvm_vcpu_arch { */ struct { u32 mdscr_el1; + bool pstate_ss; } guest_debug_preserved; /* vcpu power state */ |