virt/kvm/ppc-pv.rst

1 .. SPDX-License-Identifier: GPL-2.0
24 To find out if we're running on KVM or not, we leverage the device tree. When
25 Linux is running on KVM, a node /hypervisor exists. That node contains a
28 Once you determined you're running under a PV capable KVM, you can now use
35 'hypercall-instructions'. This property contains at most 4 opcodes that make
43 	r0		-			volatile
53 	r12		-			volatile
77 With this hypercall issued the guest always gets the magic page mapped at the
80 applicable to the target. For now, we always map the page to -4096. This way we
84 	ld	rX, -4096(0)
133   - MSR_EE
134   - MSR_RI
142 respectively on 32-bit systems with an added offset of 4 to accommodate for big
145 The following is a list of mapping the Linux kernel performs when running as
153 mfmsr	rX		ld	rX, magic_page->msr
154 mfsprg	rX, 0		ld	rX, magic_page->sprg0
155 mfsprg	rX, 1		ld	rX, magic_page->sprg1
156 mfsprg	rX, 2		ld	rX, magic_page->sprg2
157 mfsprg	rX, 3		ld	rX, magic_page->sprg3
158 mfsrr0	rX		ld	rX, magic_page->srr0
159 mfsrr1	rX		ld	rX, magic_page->srr1
160 mfdar	rX		ld	rX, magic_page->dar
161 mfdsisr	rX		lwz	rX, magic_page->dsisr
163 mtmsr	rX		std	rX, magic_page->msr
164 mtsprg	0, rX		std	rX, magic_page->sprg0
165 mtsprg	1, rX		std	rX, magic_page->sprg1
166 mtsprg	2, rX		std	rX, magic_page->sprg2
167 mtsprg	3, rX		std	rX, magic_page->sprg3
168 mtsrr0	rX		std	rX, magic_page->srr0
169 mtsrr1	rX		std	rX, magic_page->srr1
170 mtdar	rX		std	rX, magic_page->dar
171 mtdsisr	rX		stw	rX, magic_page->dsisr
212 PAPR hypercalls are needed to run server PowerPC PAPR guests (-M pseries in QEMU).
219 Mac-on-Linux is another user of KVM on PowerPC, which has its own hypercall (long