From e51014763540c7c4458445ea8e72c3c2efc122ab Mon Sep 17 00:00:00 2001 From: James Morse Date: Thu, 27 Jan 2022 12:20:51 +0000 Subject: [PATCH] KVM: arm64: Stop handle_exit() from handling HVC twice when an SError occurs Prior to commit f02b3c0497d4 ("KVM: arm64: Move PC rollback on SError to HYP"), when an SError is synchronised due to another exception, KVM handles the SError first. If the guest survives, the instruction that triggered the original exception is re-exectued to handle the first exception. HVC is treated as a special case as the instruction wouldn't normally be re-exectued, as its not a trap. Commit f02b3c0497d4 didn't preserve the behaviour of the 'return 1' that skips the rest of handle_exit(). Since commit f02b3c0497d4, KVM will try to handle the SError and the original exception at the same time. When the exception was an HVC, fixup_guest_exit() has already rolled back ELR_EL2, meaning if the guest has virtual SError masked, it will execute and handle the HVC twice. Restore the original behaviour. Fixes: f02b3c0497d4 ("KVM: arm64: Move PC rollback on SError to HYP") Cc: stable@vger.kernel.org Signed-off-by: James Morse Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20220127122052.1584324-4-james.morse@arm.com --- arch/arm64/kvm/handle_exit.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index fd2dd26caf910..e3140abd2e2eb 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -228,6 +228,14 @@ int handle_exit(struct kvm_vcpu *vcpu, int exception_index) { struct kvm_run *run = vcpu->run; + if (ARM_SERROR_PENDING(exception_index)) { + /* + * The SError is handled by handle_exit_early(). If the guest + * survives it will re-execute the original instruction. + */ + return 1; + } + exception_index = ARM_EXCEPTION_CODE(exception_index); switch (exception_index) { -- 2.39.5