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| author | Fuad Tabba <tabba@google.com> | 2024-06-03 15:28:48 +0300 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2024-06-04 17:06:33 +0300 |
| commit | b5b9955617bc0b41546f2fa7c3dbcc048b43dc82 (patch) | |
| tree | 034e4b9879c431dda19c38e0dad0e2e1443dabd5 /arch/arm64/kvm/hyp/nvhe/switch.c | |
| parent | 66d5b53e20a6e00b7ce3b652a3e2db967f7b33d0 (diff) | |
| download | linux-b5b9955617bc0b41546f2fa7c3dbcc048b43dc82.tar.xz | |
KVM: arm64: Eagerly restore host fpsimd/sve state in pKVM
When running in protected mode we don't want to leak protected
guest state to the host, including whether a guest has used
fpsimd/sve. Therefore, eagerly restore the host state on guest
exit when running in protected mode, which happens only if the
guest has used fpsimd/sve.
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20240603122852.3923848-7-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Diffstat (limited to 'arch/arm64/kvm/hyp/nvhe/switch.c')
| -rw-r--r-- | arch/arm64/kvm/hyp/nvhe/switch.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c index 019f863922fa..bef74de7065b 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -184,7 +184,21 @@ static bool kvm_handle_pvm_sys64(struct kvm_vcpu *vcpu, u64 *exit_code) static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu) { - __fpsimd_save_state(*host_data_ptr(fpsimd_state)); + /* + * Non-protected kvm relies on the host restoring its sve state. + * Protected kvm restores the host's sve state as not to reveal that + * fpsimd was used by a guest nor leak upper sve bits. + */ + if (unlikely(is_protected_kvm_enabled() && system_supports_sve())) { + __hyp_sve_save_host(); + + /* Re-enable SVE traps if not supported for the guest vcpu. */ + if (!vcpu_has_sve(vcpu)) + cpacr_clear_set(CPACR_ELx_ZEN, 0); + + } else { + __fpsimd_save_state(*host_data_ptr(fpsimd_state)); + } } static const exit_handler_fn hyp_exit_handlers[] = { |