KVM: PPC: Add support for Book3S processors in hypervisor mode

This adds support for KVM running on 64-bit Book 3S processors,
specifically POWER7, in hypervisor mode.  Using hypervisor mode means
that the guest can use the processor's supervisor mode.  That means
that the guest can execute privileged instructions and access privileged
registers itself without trapping to the host.  This gives excellent
performance, but does mean that KVM cannot emulate a processor
architecture other than the one that the hardware implements.

This code assumes that the guest is running paravirtualized using the
PAPR (Power Architecture Platform Requirements) interface, which is the
interface that IBM's PowerVM hypervisor uses.  That means that existing
Linux distributions that run on IBM pSeries machines will also run
under KVM without modification.  In order to communicate the PAPR
hypercalls to qemu, this adds a new KVM_EXIT_PAPR_HCALL exit code
to include/linux/kvm.h.

Currently the choice between book3s_hv support and book3s_pr support
(i.e. the existing code, which runs the guest in user mode) has to be
made at kernel configuration time, so a given kernel binary can only
do one or the other.

This new book3s_hv code doesn't support MMIO emulation at present.
Since we are running paravirtualized guests, this isn't a serious
restriction.

With the guest running in supervisor mode, most exceptions go straight
to the guest.  We will never get data or instruction storage or segment
interrupts, alignment interrupts, decrementer interrupts, program
interrupts, single-step interrupts, etc., coming to the hypervisor from
the guest.  Therefore this introduces a new KVMTEST_NONHV macro for the
exception entry path so that we don't have to do the KVM test on entry
to those exception handlers.

We do however get hypervisor decrementer, hypervisor data storage,
hypervisor instruction storage, and hypervisor emulation assist
interrupts, so we have to handle those.

In hypervisor mode, real-mode accesses can access all of RAM, not just
a limited amount.  Therefore we put all the guest state in the vcpu.arch
and use the shadow_vcpu in the PACA only for temporary scratch space.
We allocate the vcpu with kzalloc rather than vzalloc, and we don't use
anything in the kvmppc_vcpu_book3s struct, so we don't allocate it.
We don't have a shared page with the guest, but we still need a
kvm_vcpu_arch_shared struct to store the values of various registers,
so we include one in the vcpu_arch struct.

The POWER7 processor has a restriction that all threads in a core have
to be in the same partition.  MMU-on kernel code counts as a partition
(partition 0), so we have to do a partition switch on every entry to and
exit from the guest.  At present we require the host and guest to run
in single-thread mode because of this hardware restriction.

This code allocates a hashed page table for the guest and initializes
it with HPTEs for the guest's Virtual Real Memory Area (VRMA).  We
require that the guest memory is allocated using 16MB huge pages, in
order to simplify the low-level memory management.  This also means that
we can get away without tracking paging activity in the host for now,
since huge pages can't be paged or swapped.

This also adds a few new exports needed by the book3s_hv code.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 136 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/book3s_hv_interrupts.S b/arch/powerpc/kvm/book3s_hv_interrupts.S
new file mode 100644
index 00000000000..532afaf1984
--- /dev/null
+++ b/arch/powerpc/kvm/book3s_hv_interrupts.S
@@ -0,0 +1,136 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * Copyright 2011 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
+ *
+ * Derived from book3s_interrupts.S, which is:
+ * Copyright SUSE Linux Products GmbH 2009
+ *
+ * Authors: Alexander Graf <agraf@suse.de>
+ */
+
+#include <asm/ppc_asm.h>
+#include <asm/kvm_asm.h>
+#include <asm/reg.h>
+#include <asm/page.h>
+#include <asm/asm-offsets.h>
+#include <asm/exception-64s.h>
+#include <asm/ppc-opcode.h>
+
+/*****************************************************************************
+ *                                                                           *
+ *     Guest entry / exit code that is in kernel module memory (vmalloc)     *
+ *                                                                           *
+ ****************************************************************************/
+
+/* Registers:
+ *  r4: vcpu pointer
+ */
+_GLOBAL(__kvmppc_vcore_entry)
+
+	/* Write correct stack frame */
+	mflr	r0
+	std	r0,PPC_LR_STKOFF(r1)
+
+	/* Save host state to the stack */
+	stdu	r1, -SWITCH_FRAME_SIZE(r1)
+
+	/* Save non-volatile registers (r14 - r31) */
+	SAVE_NVGPRS(r1)
+
+	/* Save host DSCR */
+	mfspr	r3, SPRN_DSCR
+	std	r3, HSTATE_DSCR(r13)
+
+	/* Save host DABR */
+	mfspr	r3, SPRN_DABR
+	std	r3, HSTATE_DABR(r13)
+
+	/* Hard-disable interrupts */
+	mfmsr   r10
+	std	r10, HSTATE_HOST_MSR(r13)
+	rldicl  r10,r10,48,1
+	rotldi  r10,r10,16
+	mtmsrd  r10,1
+
+	/* Save host PMU registers and load guest PMU registers */
+	/* R4 is live here (vcpu pointer) but not r3 or r5 */
+	li	r3, 1
+	sldi	r3, r3, 31		/* MMCR0_FC (freeze counters) bit */
+	mfspr	r7, SPRN_MMCR0		/* save MMCR0 */
+	mtspr	SPRN_MMCR0, r3		/* freeze all counters, disable interrupts */
+	isync
+	ld	r3, PACALPPACAPTR(r13)	/* is the host using the PMU? */
+	lbz	r5, LPPACA_PMCINUSE(r3)
+	cmpwi	r5, 0
+	beq	31f			/* skip if not */
+	mfspr	r5, SPRN_MMCR1
+	mfspr	r6, SPRN_MMCRA
+	std	r7, HSTATE_MMCR(r13)
+	std	r5, HSTATE_MMCR + 8(r13)
+	std	r6, HSTATE_MMCR + 16(r13)
+	mfspr	r3, SPRN_PMC1
+	mfspr	r5, SPRN_PMC2
+	mfspr	r6, SPRN_PMC3
+	mfspr	r7, SPRN_PMC4
+	mfspr	r8, SPRN_PMC5
+	mfspr	r9, SPRN_PMC6
+	stw	r3, HSTATE_PMC(r13)
+	stw	r5, HSTATE_PMC + 4(r13)
+	stw	r6, HSTATE_PMC + 8(r13)
+	stw	r7, HSTATE_PMC + 12(r13)
+	stw	r8, HSTATE_PMC + 16(r13)
+	stw	r9, HSTATE_PMC + 20(r13)
+31:
+
+	/*
+	 * Put whatever is in the decrementer into the
+	 * hypervisor decrementer.
+	 */
+	mfspr	r8,SPRN_DEC
+	mftb	r7
+	mtspr	SPRN_HDEC,r8
+	extsw	r8,r8
+	add	r8,r8,r7
+	std	r8,HSTATE_DECEXP(r13)
+
+	/* Jump to partition switch code */
+	bl	.kvmppc_hv_entry_trampoline
+	nop
+
+/*
+ * We return here in virtual mode after the guest exits
+ * with something that we can't handle in real mode.
+ * Interrupts are enabled again at this point.
+ */
+
+.global kvmppc_handler_highmem
+kvmppc_handler_highmem:
+
+	/*
+	 * Register usage at this point:
+	 *
+	 * R1       = host R1
+	 * R2       = host R2
+	 * R12      = exit handler id
+	 * R13      = PACA
+	 */
+
+	/* Restore non-volatile host registers (r14 - r31) */
+	REST_NVGPRS(r1)
+
+	addi    r1, r1, SWITCH_FRAME_SIZE
+	ld	r0, PPC_LR_STKOFF(r1)
+	mtlr	r0
+	blr