From 5a5e65361f01b44caa51ba202e6720d458829fc5 Mon Sep 17 00:00:00 2001 From: Matthew Rosato Date: Tue, 29 Jan 2013 11:48:20 -0500 Subject: [PATCH] KVM: s390: Intercept the tprot instruction Based on original patch from Jeng-fang (Nick) Wang When standby memory is specified for a guest Linux, but no virtual memory has been allocated on the Qemu host backing that guest, the guest memory detection process encounters a memory access exception which is not thrown from the KVM handle_tprot() instruction-handler function. The access exception comes from sie64a returning EFAULT, which then passes an addressing exception to the guest. Unfortunately this does not the proper PSW fixup (nullifying vs. suppressing) so the guest will get a fault for the wrong address. Let's just intercept the tprot instruction all the time to do the right thing and not go the page fault handler path for standby memory. tprot is only used by Linux during startup so some exits should be ok. Without this patch, standby memory cannot be used with KVM. Signed-off-by: Nick Wang Reviewed-by: Christian Borntraeger Reviewed-by: Cornelia Huck Tested-by: Matthew Rosato Signed-off-by: Christian Borntraeger --- arch/s390/include/asm/kvm_host.h | 1 + arch/s390/kvm/kvm-s390.c | 4 +++- 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index a27f5007062a..4181d7baabba 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -110,6 +110,7 @@ struct kvm_s390_sie_block { #define ICTL_ISKE 0x00004000 #define ICTL_SSKE 0x00002000 #define ICTL_RRBE 0x00001000 +#define ICTL_TPROT 0x00000200 __u32 ictl; /* 0x0048 */ __u32 eca; /* 0x004c */ #define ICPT_INST 0x04 diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 06d1888f9179..43e191b25789 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -637,7 +637,9 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu) if (sclp_has_siif()) vcpu->arch.sie_block->eca |= 1; vcpu->arch.sie_block->fac = (int) (long) vfacilities; - vcpu->arch.sie_block->ictl |= ICTL_ISKE | ICTL_SSKE | ICTL_RRBE; + vcpu->arch.sie_block->ictl |= ICTL_ISKE | ICTL_SSKE | ICTL_RRBE | + ICTL_TPROT; + if (kvm_s390_cmma_enabled(vcpu->kvm)) { rc = kvm_s390_vcpu_setup_cmma(vcpu); if (rc) -- 2.30.2