From ac0fbbb2d02bc68b3c0bbc873e40dc0d75e71f4d Mon Sep 17 00:00:00 2001 From: Aditya Gupta Date: Wed, 31 Jul 2024 11:20:20 +0530 Subject: target/ppc: Fix regression due to Power10 and Power11 having same PCR Power11 has the same PCR (Processor Compatibility Register) value, as Power10. Due to this, QEMU considers Power11 as a valid compat-mode for Power10, ie. earlier it was possible to run QEMU with '-M pseries,max-compat-mode=power11 --cpu power10' Same PCR also introduced a regression where `-M pseries --cpu power10` boots as Power11 (ie. logical PVR is of Power11, even though PVR is Power10). The regression was due to 'do_client_architecture_support' checking for valid compat modes and finding Power11 to be a valid compat mode for Power10 (it happens even without passing 'max-compat-mode' explicitly). Fix compat-mode issue and regression, by ensuring a future Power processor (with a higher logical_pvr value, eg. P11) cannot be valid compat-mode for an older Power processor (eg. P10) Reviewed-by: Nicholas Piggin Signed-off-by: Aditya Gupta Tested-by: Amit Machhiwal Signed-off-by: Nicholas Piggin --- target/ppc/compat.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/target/ppc/compat.c b/target/ppc/compat.c index ebef2cccec..5b20fd7ef0 100644 --- a/target/ppc/compat.c +++ b/target/ppc/compat.c @@ -132,6 +132,10 @@ static bool pcc_compat(PowerPCCPUClass *pcc, uint32_t compat_pvr, /* Outside specified range */ return false; } + if (compat->pvr > pcc->spapr_logical_pvr) { + /* Older CPU cannot support a newer processor's compat mode */ + return false; + } if (!(pcc->pcr_supported & compat->pcr_level)) { /* Not supported by this CPU */ return false; -- cgit v1.2.3