[kvm-unit-tests PATCH v2 08/10] lib: s390x: Introduce snippet helpers

Janosch Frank
2021-12-07T16:02:18Z

These helpers reduce code duplication for PV snippet tests.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
lib/s390x/snippet.h | 103 ++++++++++++++++++++++++++++++++++++++++++++
lib/s390x/uv.h | 21 +++++++++
2 files changed, 124 insertions(+)

diff --git a/lib/s390x/snippet.h b/lib/s390x/snippet.h
index 6b77a8a9..b17b2a4c 100644
--- a/lib/s390x/snippet.h
+++ b/lib/s390x/snippet.h
@@ -9,6 +9,10 @@
#ifndef _S390X_SNIPPET_H_
#define _S390X_SNIPPET_H_

+#include <sie.h>
+#include <uv.h>
+#include <asm/uv.h>
+
/* This macro cuts down the length of the pointers to snippets */
#define SNIPPET_NAME_START(type, file) \
_binary_s390x_snippets_##type##_##file##_gbin_start
@@ -26,6 +30,12 @@
#define SNIPPET_HDR_LEN(type, file) \
((uintptr_t)SNIPPET_HDR_END(type, file) - (uintptr_t)SNIPPET_HDR_START(type, file))

+#define SNIPPET_PV_TWEAK0 0x42UL
+#define SNIPPET_PV_TWEAK1 0UL
+#define SNIPPET_OFF_C 0
+#define SNIPPET_OFF_ASM 0x4000
+
+
/*
* C snippet instructions start at 0x4000 due to the prefix and the
* stack being before that. ASM snippets don't strictly need a stack
@@ -38,4 +48,97 @@ static const struct psw snippet_psw = {
.mask = PSW_MASK_64,
.addr = SNIPPET_ENTRY_ADDR,
};
+
+/*
+ * Sets up a snippet guest on top of an existing and initialized SIE
+ * vm struct.
+ * Once this function has finished without errors the guest can be started.
+ *
+ * @vm: VM that this function will populated, has to be initialized already
+ * @gbin: Snippet gbin data pointer
+ * @gbin_len: Length of the gbin data
+ * @off: Offset from guest absolute 0x0 where snippet is copied to
+ */
+static inline void snippet_init(struct vm *vm, const char *gbin,
+ uint64_t gbin_len, uint64_t off)
+{
+ uint64_t mso = vm->sblk->mso;
+
+ /* Copy test image to guest memory */
+ memcpy((void *)mso + off, gbin, gbin_len);
+
+ /* Setup guest PSW */
+ vm->sblk->gpsw = snippet_psw;
+
+ /*
+ * We want to exit on PGM exceptions so we don't need
+ * exception handlers in the guest.
+ */
+ vm->sblk->ictl = ICTL_OPEREXC | ICTL_PINT;
+}
+
+/*
+ * Sets up a snippet UV/PV guest on top of an existing and initialized
+ * SIE vm struct.
+ * Once this function has finished without errors the guest can be started.
+ *
+ * @vm: VM that this function will populated, has to be initialized already
+ * @gbin: Snippet gbin data pointer
+ * @hdr: Snippet SE header data pointer
+ * @gbin_len: Length of the gbin data
+ * @hdr_len: Length of the hdr data
+ * @off: Offset from guest absolute 0x0 where snippet is copied to
+ */
+static inline void snippet_pv_init(struct vm *vm, const char *gbin,
+ const char *hdr, uint64_t gbin_len,
+ uint64_t hdr_len, uint64_t off)
+{
+ uint64_t tweak[2] = {SNIPPET_PV_TWEAK0, SNIPPET_PV_TWEAK1};
+ uint64_t mso = vm->sblk->mso;
+ int i;
+
+ snippet_init(vm, gbin, gbin_len, off);
+
+ uv_create_guest(vm);
+ uv_set_se_hdr(vm->uv.vm_handle, (void *)hdr, hdr_len);
+
+ /* Unpack works on guest addresses so we only need off */
+ uv_unpack(vm, off, gbin_len, tweak[0]);
+ uv_verify_load(vm);
+
+ /*
+ * Manually import:
+ * - lowcore 0x0 - 0x1000 (asm)
+ * - stack 0x3000 (C)
+ */
+ for (i = 0; i < 4; i++) {
+ uv_import(vm->uv.vm_handle, mso + PAGE_SIZE * i);
+ }
+}
+
+/* Allocates and sets up a snippet based guest */
+static inline void snippet_setup_guest(struct vm *vm, bool is_pv)
+{
+ u8 *guest;
+
+ /* Allocate 1MB as guest memory */
+ guest = alloc_pages(8);
+ memset(guest, 0, HPAGE_SIZE);
+
+ /* Initialize the vm struct and allocate control blocks */
+ sie_guest_create(vm, (uint64_t)guest, HPAGE_SIZE);
+
+ if (is_pv) {
+ /* FMT4 needs a ESCA */
+ sie_guest_sca_create(vm);
+
+ /*
+ * Initialize UV and setup the address spaces needed
+ * to run a PV guest.
+ */
+ uv_init();
+ uv_setup_asces();
+ }
+}
+
#endif
diff --git a/lib/s390x/uv.h b/lib/s390x/uv.h
index 6ffe537a..8175d9c6 100644
--- a/lib/s390x/uv.h
+++ b/lib/s390x/uv.h
@@ -3,6 +3,7 @@
#define _S390X_UV_H_

#include <sie.h>
+#include <asm/pgtable.h>

bool uv_os_is_guest(void);
bool uv_os_is_host(void);
@@ -14,4 +15,24 @@ void uv_destroy_guest(struct vm *vm);
int uv_unpack(struct vm *vm, uint64_t addr, uint64_t len, uint64_t tweak);
void uv_verify_load(struct vm *vm);

+/*
+ * To run PV guests we need to setup a few things:
+ * - A valid primary ASCE that contains the guest memory and has the P bit set.
+ * - A valid home space ASCE for the UV calls that use home space addresses.
+ */
+static inline void uv_setup_asces(void)
+{
+ uint64_t asce;
+
+ /* We need to have a valid primary ASCE to run guests. */
+ setup_vm();
+
+ /* Set P bit in ASCE as it is required for PV guests */
+ asce = stctg(1) | ASCE_P;
+ lctlg(1, asce);
+
+ /* Copy ASCE into home space CR */
+ lctlg(13, asce);
+}
+
#endif /* UV_H */
--
2.32.0