From f0638a0b6bba455e8eaf518f23487d6ff1f59b5a Mon Sep 17 00:00:00 2001 From: Fabiano Rosas Date: Fri, 11 Sep 2020 01:31:23 -0300 Subject: [PATCH] spapr: Handle HPT allocation failure in nested guest The nested KVM code does not yet support HPT guests. Calling the KVM_CAP_PPC_ALLOC_HTAB ioctl currently leads to KVM setting the guest as HPT and erroneously executing code in L1 that should only run in hypervisor mode, leading to an exception in the L1 vcpu thread when it enters the nested guest. This can be reproduced with -machine max-cpu-compat=power8 in the L2 guest command line. The KVM code has since been modified to fail the ioctl when running in a nested environment so QEMU needs to be able to handle that. This patch provides an error message informing the user about the lack of support for HPT in nested guests. Reported-by: Satheesh Rajendran Signed-off-by: Fabiano Rosas Message-Id: <20200911043123.204162-1-farosas@linux.ibm.com> Reviewed-by: Greg Kurz Signed-off-by: David Gibson --- hw/ppc/spapr.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index 2db810f73a..544a1947d9 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -1483,6 +1483,12 @@ void spapr_reallocate_hpt(SpaprMachineState *spapr, int shift, spapr_free_hpt(spapr); rc = kvmppc_reset_htab(shift); + + if (rc == -EOPNOTSUPP) { + error_setg(errp, "HPT not supported in nested guests"); + return; + } + if (rc < 0) { /* kernel-side HPT needed, but couldn't allocate one */ error_setg_errno(errp, errno, -- 2.30.2