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KVM: arm64: Move PC rollback on SError to HYP

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Instead of handling the "PC rollback on SError during HVC" at EL1 (which
requires disclosing PC to a potentially untrusted kernel), let's move
this fixup to ... fixup_guest_exit(), which is where we do all fixups.

Isn't that neat?

Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2020-10-14 12:12:45 +01:00
parent cdb5e02ed1
commit defe21f49b
2 changed files with 15 additions and 17 deletions
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17
arch/arm64/kvm/handle_exit.c
View File

@ -241,23 +241,6 @@ int handle_exit(struct kvm_vcpu *vcpu, int exception_index)
{
struct kvm_run *run = vcpu->run;
if (ARM_SERROR_PENDING(exception_index)) {
u8 esr_ec = ESR_ELx_EC(kvm_vcpu_get_esr(vcpu));
/*
* HVC already have an adjusted PC, which we need to
* correct in order to return to after having injected
* the SError.
*
* SMC, on the other hand, is *trapped*, meaning its
* preferred return address is the SMC itself.
*/
if (esr_ec == ESR_ELx_EC_HVC32 || esr_ec == ESR_ELx_EC_HVC64)
*vcpu_pc(vcpu) -= 4;
return 1;
}
exception_index = ARM_EXCEPTION_CODE(exception_index);
switch (exception_index) {

15
arch/arm64/kvm/hyp/include/hyp/switch.h
View File

@ -411,6 +411,21 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
if (ARM_EXCEPTION_CODE(*exit_code) != ARM_EXCEPTION_IRQ)
vcpu->arch.fault.esr_el2 = read_sysreg_el2(SYS_ESR);
if (ARM_SERROR_PENDING(*exit_code)) {
u8 esr_ec = kvm_vcpu_trap_get_class(vcpu);
/*
* HVC already have an adjusted PC, which we need to
* correct in order to return to after having injected
* the SError.
*
* SMC, on the other hand, is *trapped*, meaning its
* preferred return address is the SMC itself.
*/
if (esr_ec == ESR_ELx_EC_HVC32 || esr_ec == ESR_ELx_EC_HVC64)
write_sysreg_el2(read_sysreg_el2(SYS_ELR) - 4, SYS_ELR);
}
/*
* We're using the raw exception code in order to only process
* the trap if no SError is pending. We will come back to the