From patchwork Thu Jul 11 11:49:43 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Mackerras X-Patchwork-Id: 258416 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id C3ACD2C031D for ; Thu, 11 Jul 2013 21:57:00 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754447Ab3GKL47 (ORCPT ); Thu, 11 Jul 2013 07:56:59 -0400 Received: from ozlabs.org ([203.10.76.45]:60676 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751210Ab3GKL46 (ORCPT ); Thu, 11 Jul 2013 07:56:58 -0400 Received: by ozlabs.org (Postfix, from userid 1003) id AD0F72C0312; Thu, 11 Jul 2013 21:56:57 +1000 (EST) Date: Thu, 11 Jul 2013 21:49:43 +1000 From: Paul Mackerras To: Alexander Graf Cc: kvm-ppc@vger.kernel.org, kvm@vger.kernel.org Subject: [PATCH 1/8] KVM: PPC: Book3S PR: Load up SPRG3 register with guest value on guest entry Message-ID: <20130711114943.GC21353@iris.ozlabs.ibm.com> References: <20130711114839.GB21353@iris.ozlabs.ibm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20130711114839.GB21353@iris.ozlabs.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org Unlike the other general-purpose SPRs, SPRG3 can be read by usermode code, and is used in recent kernels to store the CPU and NUMA node numbers so that they can be read by VDSO functions. Thus we need to load the guest's SPRG3 value into the real SPRG3 register when entering the guest, and restore the host's value when exiting the guest. We don't need to save the guest SPRG3 value when exiting the guest as usermode code can't modify SPRG3. Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/asm-offsets.c | 1 + arch/powerpc/kvm/book3s_interrupts.S | 14 ++++++++++++++ 2 files changed, 15 insertions(+) diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 6f16ffa..a67c76e 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -452,6 +452,7 @@ int main(void) DEFINE(VCPU_SPRG2, offsetof(struct kvm_vcpu, arch.shregs.sprg2)); DEFINE(VCPU_SPRG3, offsetof(struct kvm_vcpu, arch.shregs.sprg3)); #endif + DEFINE(VCPU_SHARED_SPRG3, offsetof(struct kvm_vcpu_arch_shared, sprg3)); DEFINE(VCPU_SHARED_SPRG4, offsetof(struct kvm_vcpu_arch_shared, sprg4)); DEFINE(VCPU_SHARED_SPRG5, offsetof(struct kvm_vcpu_arch_shared, sprg5)); DEFINE(VCPU_SHARED_SPRG6, offsetof(struct kvm_vcpu_arch_shared, sprg6)); diff --git a/arch/powerpc/kvm/book3s_interrupts.S b/arch/powerpc/kvm/book3s_interrupts.S index 48cbbf8..17cfae5 100644 --- a/arch/powerpc/kvm/book3s_interrupts.S +++ b/arch/powerpc/kvm/book3s_interrupts.S @@ -92,6 +92,11 @@ kvm_start_lightweight: PPC_LL r3, VCPU_HFLAGS(r4) rldicl r3, r3, 0, 63 /* r3 &= 1 */ stb r3, HSTATE_RESTORE_HID5(r13) + + /* Load up guest SPRG3 value, since it's user readable */ + ld r3, VCPU_SHARED(r4) + ld r3, VCPU_SHARED_SPRG3(r3) + mtspr SPRN_SPRG3, r3 #endif /* CONFIG_PPC_BOOK3S_64 */ PPC_LL r4, VCPU_SHADOW_MSR(r4) /* get shadow_msr */ @@ -123,6 +128,15 @@ kvmppc_handler_highmem: /* R7 = vcpu */ PPC_LL r7, GPR4(r1) +#ifdef CONFIG_PPC_BOOK3S_64 + /* + * Reload kernel SPRG3 value. + * No need to save guest value as usermode can't modify SPRG3. + */ + ld r3, PACA_SPRG3(r13) + mtspr SPRN_SPRG3, r3 +#endif /* CONFIG_PPC_BOOK3S_64 */ + PPC_STL r14, VCPU_GPR(R14)(r7) PPC_STL r15, VCPU_GPR(R15)(r7) PPC_STL r16, VCPU_GPR(R16)(r7)