[RFC PATCH 07/10] KVM: PPC: BOOK3S: PR: Emulate facility status and control register

[Aneesh Kumar K.V]

We allow priv-mode update of this. The guest value is saved in fscr,
and the value actually used is saved in shadow_fscr. shadow_fscr
only contains values that are allowed by the host. On
facility unavailable interrupt, if the facility is allowed by fscr
but disabled in shadow_fscr we need to emulate the support. Currently
all but EBB is disabled. We still don't support performance monitoring
in PR guest.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/kvm_book3s_asm.h |  1 +
 arch/powerpc/include/asm/kvm_host.h       |  1 +
 arch/powerpc/kernel/asm-offsets.c         |  2 ++
 arch/powerpc/kvm/book3s_emulate.c         | 16 ++++++++++++++++
 arch/powerpc/kvm/book3s_interrupts.S      | 25 ++++++++++++++++++++++---
 5 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_book3s_asm.h b/arch/powerpc/include/asm/kvm_book3s_asm.h
index 192917d2239c..abd42523ad93 100644
--- a/arch/powerpc/include/asm/kvm_book3s_asm.h
+++ b/arch/powerpc/include/asm/kvm_book3s_asm.h
@@ -103,6 +103,7 @@ struct kvmppc_host_state {
 #ifdef CONFIG_PPC_BOOK3S_64
 	u64 cfar;
 	u64 ppr;
+	u64 host_fscr;
 #endif
 };
 
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index e0b13aca98e6..f4be7be14330 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -478,6 +478,7 @@ struct kvm_vcpu_arch {
 	ulong ppr;
 	ulong pspb;
 	ulong fscr;
+	ulong shadow_fscr;
 	ulong tfhar;
 	ulong tfiar;
 	ulong texasr;
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 2c2227da6917..7484676b8f25 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -525,6 +525,7 @@ int main(void)
 	DEFINE(VCPU_CFAR, offsetof(struct kvm_vcpu, arch.cfar));
 	DEFINE(VCPU_PPR, offsetof(struct kvm_vcpu, arch.ppr));
 	DEFINE(VCPU_FSCR, offsetof(struct kvm_vcpu, arch.fscr));
+	DEFINE(VCPU_SHADOW_FSCR, offsetof(struct kvm_vcpu, arch.shadow_fscr));
 	DEFINE(VCPU_PSPB, offsetof(struct kvm_vcpu, arch.pspb));
 	DEFINE(VCPU_TFHAR, offsetof(struct kvm_vcpu, arch.tfhar));
 	DEFINE(VCPU_TFIAR, offsetof(struct kvm_vcpu, arch.tfiar));
@@ -626,6 +627,7 @@ int main(void)
 #ifdef CONFIG_PPC_BOOK3S_64
 	HSTATE_FIELD(HSTATE_CFAR, cfar);
 	HSTATE_FIELD(HSTATE_PPR, ppr);
+	HSTATE_FIELD(HSTATE_FSCR, host_fscr);
 #endif /* CONFIG_PPC_BOOK3S_64 */
 
 #else /* CONFIG_PPC_BOOK3S */
diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
index 7f25adbd2590..60d0b6b745e7 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c
@@ -468,6 +468,19 @@ int kvmppc_core_emulate_mtspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 	case SPRN_MSSSR0:
 	case SPRN_DABR:
 		break;
+	case SPRN_FSCR:
+	{
+		ulong host_fscr = mfspr(SPRN_FSCR);
+		/*
+		 * We disable FSCR_EBB for pr guest. TAR and DSCR are always
+		 * enabled.
+		 */
+		if (spr_val & ~(FSCR_TAR|FSCR_DSCR|FSCR_EBB))
+			pr_info("KVM: invalud FSCR value 0x%lx", spr_val);
+		vcpu->arch.fscr = spr_val & (FSCR_TAR|FSCR_DSCR);
+		vcpu->arch.shadow_fscr = vcpu->arch.fscr & host_fscr;
+		break;
+	}
 unprivileged:
 	default:
 		printk(KERN_INFO "KVM: invalid SPR write: %d\n", sprn);
@@ -591,6 +604,9 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val
 		 */
 		*spr_val = 0;
 		break;
+	case SPRN_FSCR:
+		*spr_val = vcpu->arch.fscr;
+		break;
 	default:
 unprivileged:
 		printk(KERN_INFO "KVM: invalid SPR read: %d\n", sprn);
diff --git a/arch/powerpc/kvm/book3s_interrupts.S b/arch/powerpc/kvm/book3s_interrupts.S
index f779450cb07c..fcbdf4817301 100644
--- a/arch/powerpc/kvm/book3s_interrupts.S
+++ b/arch/powerpc/kvm/book3s_interrupts.S
@@ -107,6 +107,14 @@ kvm_start_lightweight:
 	ld	r3, VCPU_SHARED(r4)
 	ld	r3, VCPU_SHARED_SPRG3(r3)
 	mtspr	SPRN_SPRG3, r3
+
+BEGIN_FTR_SECTION
+	mfspr r3,SPRN_FSCR
+	PPC_STL	r3, HSTATE_FSCR(r13)
+
+	PPC_LL r3, VCPU_SHADOW_FSCR(r4)
+	mtspr SPRN_FSCR, r3
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 #endif /* CONFIG_PPC_BOOK3S_64 */
 
 	PPC_LL	r4, VCPU_SHADOW_MSR(r4)	/* get shadow_msr */
@@ -148,6 +156,9 @@ kvm_start_lightweight:
 	bl	FUNC(kvmppc_copy_from_svcpu)
 	nop
 
+	/* R7 = vcpu */
+	PPC_LL	r7, GPR4(r1)
+
 #ifdef CONFIG_PPC_BOOK3S_64
 	/*
 	 * Reload kernel SPRG3 value.
@@ -155,10 +166,18 @@ kvm_start_lightweight:
 	 */
 	ld	r3, PACA_SPRG3(r13)
 	mtspr	SPRN_SPRG3, r3
-#endif /* CONFIG_PPC_BOOK3S_64 */
+BEGIN_FTR_SECTION
+	/*
+	 * Save the current fscr in shadow fscr
+	 */
+	mfspr r3,SPRN_FSCR
+	PPC_STL r3, VCPU_SHADOW_FSCR(r7)
 
-	/* R7 = vcpu */
-	PPC_LL	r7, GPR4(r1)
+	PPC_LL	r3, HSTATE_FSCR(r13)
+	mtspr	SPRN_FSCR, r3
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
+
+#endif /* CONFIG_PPC_BOOK3S_64 */
 
 	PPC_STL	r14, VCPU_GPR(R14)(r7)
 	PPC_STL	r15, VCPU_GPR(R15)(r7)
-- 
1.8.5.3