Re: [RFC PATCH] powerpc/64s: remove POWER9 DD1 support

On Sun, 10 Jun 2018 22:58:11 +0200
Michal Such=C3=A1nek [off-list ref] wrote:

On Sun, 10 Jun 2018 23:30:27 +1000
Nicholas Piggin [off-list ref] wrote:
=20

quoted

POWER9 DD1 was never a product. It is no longer supported by upstream
firmware, and it is not effectively supported in Linux due to lack of
testing.
 =20

=20

quoted

diff --git a/arch/powerpc/kvm/book3s_xive_template.c

b/arch/powerpc/kvm/book3s_xive_template.c index
99c3620b40d9..487f1f6650cc 100644 ---
a/arch/powerpc/kvm/book3s_xive_template.c +++
b/arch/powerpc/kvm/book3s_xive_template.c @@ -25,18 +25,6 @@ static
void GLUE(X_PFX,ack_pending)(struct kvmppc_xive_vcpu *xc) */
 	eieio();
=20
-	/*
-	 * DD1 bug workaround: If PIPR is less favored than CPPR
-	 * ignore the interrupt or we might incorrectly lose an IPB
-	 * bit.
-	 */
-	if (cpu_has_feature(CPU_FTR_POWER9_DD1)) {
-		__be64 qw1 =3D __x_readq(__x_tima + TM_QW1_OS);
-		u8 pipr =3D be64_to_cpu(qw1) & 0xff;
-		if (pipr >=3D xc->hw_cppr)
-			return;
-	}
-
 	/* Perform the acknowledge OS to register cycle. */
 	ack =3D be16_to_cpu(__x_readw(__x_tima + TM_SPC_ACK_OS_REG));
=20

@@ -105,7 +93,7 @@ static void GLUE(X_PFX,source_eoi)(u32 hw_irq,

struct xive_irq_data *xd) *
 		 * For LSIs, using the HW EOI cycle works around a
problem
 		 * on P9 DD1 PHBs where the other ESB accesses don't
work
-		 * properly.
+		 * properly. XXX: can this be removed?
 		 */
 		if (xd->flags & XIVE_IRQ_FLAG_LSI)
 			__x_readq(__x_eoi_page(xd) + =20

=20
Maybe this should be really removed or the comment changed to why it is
still useful?

Good point, I meant to ask Ben about that.

Thanks,
Nick