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spapr/xive: Sanity checks of OV5 during CAS

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If a machine is started with ic-mode=xive but the guest only knows
about XICS, eg. an RHEL 7.6 guest, the kernel panics. This is
expected but a bit unfortunate since the crash doesn't provide
much information for the end user to guess what's happening.

Detect that during CAS and exit QEMU with a proper error message
instead, like it is already done for the MMU.

Even if this is less likely to happen, the opposite case of a guest
that only knows about XIVE would certainly fail all the same if the
machine is started with ic-mode=xics.

Also, the only valid values a guest can pass in byte 23 of OV5 during
CAS are 0b00 (XIVE legacy mode) and 0b01 (XIVE exploitation mode). Any
other value is a bug, at least with the current spec. Again, it does
not seem right to let the guest go on without a precise idea of the
interrupt mode it asked for.

Handle these cases as well.

Reported-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <155793986451.464434.12887933000007255549.stgit@bahia.lan>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Greg Kurz 2019-05-15 19:04:24 +02:00 committed by David Gibson
parent 77bd8937c0
commit e7f78db9fb
1 changed files with 24 additions and 0 deletions
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24
hw/ppc/spapr_hcall.c
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@ -1513,6 +1513,7 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
bool guest_radix;
Error *local_err = NULL;
bool raw_mode_supported = false;
bool guest_xive;
cas_pvr = cas_check_pvr(spapr, cpu, &addr, &raw_mode_supported, &local_err);
if (local_err) {
@ -1545,10 +1546,17 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
error_report("guest requested hash and radix MMU, which is invalid.");
exit(EXIT_FAILURE);
}
if (spapr_ovec_test(ov5_guest, OV5_XIVE_BOTH)) {
error_report("guest requested an invalid interrupt mode");
exit(EXIT_FAILURE);
}
/* The radix/hash bit in byte 24 requires special handling: */
guest_radix = spapr_ovec_test(ov5_guest, OV5_MMU_RADIX_300);
spapr_ovec_clear(ov5_guest, OV5_MMU_RADIX_300);
guest_xive = spapr_ovec_test(ov5_guest, OV5_XIVE_EXPLOIT);
/*
* HPT resizing is a bit of a special case, because when enabled
* we assume an HPT guest will support it until it says it
@ -1632,6 +1640,22 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
ov5_updates) != 0);
}
/*
* Ensure the guest asks for an interrupt mode we support; otherwise
* terminate the boot.
*/
if (guest_xive) {
if (spapr->irq->ov5 == SPAPR_OV5_XIVE_LEGACY) {
error_report("Guest requested unavailable interrupt mode (XIVE)");
exit(EXIT_FAILURE);
}
} else {
if (spapr->irq->ov5 == SPAPR_OV5_XIVE_EXPLOIT) {
error_report("Guest requested unavailable interrupt mode (XICS)");
exit(EXIT_FAILURE);
}
}
/*
* Generate a machine reset when we have an update of the
* interrupt mode. Only required when the machine supports both