From b24f36f33ea088771c2bb7c09e84d0ddea35cf55 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Tue, 25 Mar 2014 10:47:04 +1100 Subject: [PATCH] KVM: PPC: Book3S: Trim top 4 bits of physical address in RTAS code The in-kernel emulation of RTAS functions needs to read the argument buffer from guest memory in order to find out what function is being requested. The guest supplies the guest physical address of the buffer, and on a real system the code that reads that buffer would run in guest real mode. In guest real mode, the processor ignores the top 4 bits of the address specified in load and store instructions. In order to emulate that behaviour correctly, we need to mask off those bits before calling kvm_read_guest() or kvm_write_guest(). This adds that masking. Signed-off-by: Paul Mackerras Acked-by: Scott Wood --- arch/powerpc/kvm/book3s_rtas.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kvm/book3s_rtas.c b/arch/powerpc/kvm/book3s_rtas.c index cf95cdef73c9..7a053157483b 100644 --- a/arch/powerpc/kvm/book3s_rtas.c +++ b/arch/powerpc/kvm/book3s_rtas.c @@ -213,8 +213,11 @@ int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu) gpa_t args_phys; int rc; - /* r4 contains the guest physical address of the RTAS args */ - args_phys = kvmppc_get_gpr(vcpu, 4); + /* + * r4 contains the guest physical address of the RTAS args + * Mask off the top 4 bits since this is a guest real address + */ + args_phys = kvmppc_get_gpr(vcpu, 4) & KVM_PAM; rc = kvm_read_guest(vcpu->kvm, args_phys, &args, sizeof(args)); if (rc) -- 2.39.2