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arm: Fix SMC reporting to EL2 when QEMU provides PSCI

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This properly forwards SMC events to EL2 when PSCI is provided by QEMU
itself and, thus, ARM_FEATURE_EL3 is off.

Found and tested with the Jailhouse hypervisor. Solution based on
suggestions by Peter Maydell.

Backports commit 77077a83006c3c9bdca496727f1735a3c5c5355d from qemu
This commit is contained in:
Jan Kiszka 2018-03-05 01:19:12 -05:00 committed by Lioncash
parent 0741c3880a
commit ae16a26c20
No known key found for this signature in database
GPG key ID: 4E3C3CC1031BA9C7
2 changed files with 25 additions and 10 deletions
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9
qemu/target/arm/helper.c
View file

@ -3330,7 +3330,14 @@ static void hcr_write(CPUARMState *env, const ARMCPRegInfo *ri, uint64_t value)
if (arm_feature(env, ARM_FEATURE_EL3)) {
valid_mask &= ~HCR_HCD;
} else {
} else if (cpu->psci_conduit != QEMU_PSCI_CONDUIT_SMC) {
/* Architecturally HCR.TSC is RES0 if EL3 is not implemented.
* However, if we're using the SMC PSCI conduit then QEMU is
* effectively acting like EL3 firmware and so the guest at
* EL2 should retain the ability to prevent EL1 from being
* able to make SMC calls into the ersatz firmware, so in
* that case HCR.TSC should be read/write.
*/
valid_mask &= ~HCR_TSC;
}

26
qemu/target/arm/op_helper.c
View file

@ -928,22 +928,30 @@ void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome)
*/
bool undef = arm_feature(env, ARM_FEATURE_AARCH64) ? smd : smd && !secure;
if (arm_is_psci_call(cpu, EXCP_SMC)) {
/* If PSCI is enabled and this looks like a valid PSCI call then
* that overrides the architecturally mandated SMC behaviour.
if (!arm_feature(env, ARM_FEATURE_EL3) &&
cpu->psci_conduit != QEMU_PSCI_CONDUIT_SMC) {
/* If we have no EL3 then SMC always UNDEFs and can't be
* trapped to EL2. PSCI-via-SMC is a sort of ersatz EL3
* firmware within QEMU, and we want an EL2 guest to be able
* to forbid its EL1 from making PSCI calls into QEMU's
* "firmware" via HCR.TSC, so for these purposes treat
* PSCI-via-SMC as implying an EL3.
*/
return;
}
if (!arm_feature(env, ARM_FEATURE_EL3)) {
/* If we have no EL3 then SMC always UNDEFs */
undef = true;
} else if (!secure && cur_el == 1 && (env->cp15.hcr_el2 & HCR_TSC)) {
/* In NS EL1, HCR controlled routing to EL2 has priority over SMD. */
/* In NS EL1, HCR controlled routing to EL2 has priority over SMD.
* We also want an EL2 guest to be able to forbid its EL1 from
* making PSCI calls into QEMU's "firmware" via HCR.TSC.
*/
raise_exception(env, EXCP_HYP_TRAP, syndrome, 2);
}
if (undef) {
/* If PSCI is enabled and this looks like a valid PSCI call then
* suppress the UNDEF -- we'll catch the SMC exception and
* implement the PSCI call behaviour there.
*/
if (undef && !arm_is_psci_call(cpu, EXCP_SMC)) {
raise_exception(env, EXCP_UDEF, syn_uncategorized(),
exception_target_el(env));
}