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Subject[PATCH 4.14 57/74] arm64: kvm: Prevent restoring stale PMSCR_EL1 for vcpu
4.14-stable review patch.  If anyone has any objections, please let me know.


From: Julien Thierry <>

commit bfe766cf65fb65e68c4764f76158718560bdcee5 upstream.

When VHE is not present, KVM needs to save and restores PMSCR_EL1 when
possible. If SPE is used by the host, value of PMSCR_EL1 cannot be saved
for the guest.
If the host starts using SPE between two save+restore on the same vcpu,
restore will write the value of PMSCR_EL1 read during the first save.

Make sure __debug_save_spe_nvhe clears the value of the saved PMSCR_EL1
when the guest cannot use SPE.

Signed-off-by: Julien Thierry <>
Cc: Christoffer Dall <>
Cc: Marc Zyngier <>
Cc: Catalin Marinas <>
Reviewed-by: Will Deacon <>
Reviewed-by: Christoffer Dall <>
Signed-off-by: Christoffer Dall <>
Signed-off-by: Greg Kroah-Hartman <>

arch/arm64/kvm/hyp/debug-sr.c | 3 +++
1 file changed, 3 insertions(+)

--- a/arch/arm64/kvm/hyp/debug-sr.c
+++ b/arch/arm64/kvm/hyp/debug-sr.c
@@ -84,6 +84,9 @@ static void __hyp_text __debug_save_spe_
u64 reg;

+ /* Clear pmscr in case of early return */
+ *pmscr_el1 = 0;
/* SPE present on this CPU? */
if (!cpuid_feature_extract_unsigned_field(read_sysreg(id_aa64dfr0_el1),

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