KVM: PPC: Book3S HV: Use ASDR for HPT guests on POWER9

POWER9 adds a register called ASDR (Access Segment Descriptor
Register), which is set by hypervisor data/instruction storage
interrupts to contain the segment descriptor for the address
being accessed, assuming the guest is using HPT translation.
(For radix guests, it contains the guest real address of the
access.)

Thus, for HPT guests on POWER9, we can use this register rather
than looking up the SLB with the slbfee. instruction.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kvm/book3s_hv_rmhandlers.S

@@ -1715,6 +1715,10 @@ kvmppc_hdsi:
 	/* HPTE not found fault or protection fault? */
 	andis.	r0, r6, (DSISR_NOHPTE | DSISR_PROTFAULT)@h
 	beq	1f			/* if not, send it to the guest */
+BEGIN_FTR_SECTION
+	mfspr	r5, SPRN_ASDR		/* on POWER9, use ASDR to get VSID */
+	b	4f
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
 	andi.	r0, r11, MSR_DR		/* data relocation enabled? */
 	beq	3f
 	clrrdi	r0, r4, 28
@@ -1791,6 +1795,10 @@ fast_interrupt_c_return:
 kvmppc_hisi:
 	andis.	r0, r11, SRR1_ISI_NOPT@h
 	beq	1f
+BEGIN_FTR_SECTION
+	mfspr	r5, SPRN_ASDR		/* on POWER9, use ASDR to get VSID */
+	b	4f
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
 	andi.	r0, r11, MSR_IR		/* instruction relocation enabled? */
 	beq	3f
 	clrrdi	r0, r10, 28