arm64: kvm: Prevent restoring stale PMSCR_EL1 for vcpu

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 <[email protected]> Cc: Christoffer Dall <[email protected]> Cc: Marc Zyngier <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: <[email protected]> Reviewed-by: Will Deacon <[email protected]> Reviewed-by: Christoffer Dall <[email protected]> Signed-off-by: Christoffer Dall <[email protected]>
lachaves · Dec 18, 2017 · bfe766c · bfe766c
1 parent 50c4c4e
commit bfe766c
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c
@@ -74,6 +74,9 @@ static void __hyp_text __debug_save_spe_nvhe(u64 *pmscr_el1)
 {
 	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),
 						  ID_AA64DFR0_PMSVER_SHIFT))