[RFC PATCH 56/73] x86/pvm: Relocate kernel image early in PVH entry

[Lai Jiangshan <jiangshanlai@gmail.com>]

From: Hou Wenlong <houwenlong.hwl@antgroup.com>

For a PIE kernel, it runs in a high virtual address in the PVH entry, so
it needs to relocate the kernel image early in the PVH entry for the PVM
guest.

Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
---
 arch/x86/include/asm/init.h       |  5 +++++
 arch/x86/kernel/head64_identity.c |  5 -----
 arch/x86/platform/pvh/enlighten.c | 22 ++++++++++++++++++++++
 arch/x86/platform/pvh/head.S      |  4 ++++
 4 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/init.h b/arch/x86/include/asm/init.h
index cc9ccf61b6bd..f78edef60253 100644
--- a/arch/x86/include/asm/init.h
+++ b/arch/x86/include/asm/init.h
@@ -4,6 +4,11 @@
 
 #define __head	__section(".head.text")
 
+#define SYM_ABS_VA(sym) ({					\
+	unsigned long __v;					\
+	asm("movabsq $" __stringify(sym) ", %0":"=r"(__v));	\
+	__v; })
+
 struct x86_mapping_info {
 	void *(*alloc_pgt_page)(void *); /* allocate buf for page table */
 	void *context;			 /* context for alloc_pgt_page */
diff --git a/arch/x86/kernel/head64_identity.c b/arch/x86/kernel/head64_identity.c
index 4e6a073d9e6c..f69f9904003c 100644
--- a/arch/x86/kernel/head64_identity.c
+++ b/arch/x86/kernel/head64_identity.c
@@ -82,11 +82,6 @@ static void __head set_kernel_map_base(unsigned long text_base)
 }
 #endif
 
-#define SYM_ABS_VA(sym) ({					\
-	unsigned long __v;					\
-	asm("movabsq $" __stringify(sym) ", %0":"=r"(__v));	\
-	__v; })
-
 static unsigned long __head sme_postprocess_startup(struct boot_params *bp, pmdval_t *pmd)
 {
 	unsigned long vaddr, vaddr_end;
diff --git a/arch/x86/platform/pvh/enlighten.c b/arch/x86/platform/pvh/enlighten.c
index 00a92cb2c814..8c64c31c971b 100644
--- a/arch/x86/platform/pvh/enlighten.c
+++ b/arch/x86/platform/pvh/enlighten.c
@@ -1,8 +1,10 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/acpi.h>
+#include <linux/pgtable.h>
 
 #include <xen/hvc-console.h>
 
+#include <asm/init.h>
 #include <asm/io_apic.h>
 #include <asm/hypervisor.h>
 #include <asm/e820/api.h>
@@ -113,6 +115,26 @@ static void __init hypervisor_specific_init(bool xen_guest)
 		xen_pvh_init(&pvh_bootparams);
 }
 
+#ifdef CONFIG_PVM_GUEST
+void pvm_relocate_kernel(unsigned long physbase);
+
+void __init pvm_update_pgtable(unsigned long physbase)
+{
+	pgdval_t *pgd;
+	pudval_t *pud;
+	unsigned long base;
+
+	pvm_relocate_kernel(physbase);
+
+	pgd = (pgdval_t *)init_top_pgt;
+	base = SYM_ABS_VA(_text);
+	pgd[pgd_index(base)] = pgd[0];
+	pgd[pgd_index(page_offset_base)] = pgd[0];
+	pud = (pudval_t *)level3_ident_pgt;
+	pud[pud_index(base)] = (unsigned long)level2_ident_pgt + _KERNPG_TABLE_NOENC;
+}
+#endif
+
 /*
  * This routine (and those that it might call) should not use
  * anything that lives in .bss since that segment will be cleared later.
diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S
index baaa3fe34a00..127f297f7257 100644
--- a/arch/x86/platform/pvh/head.S
+++ b/arch/x86/platform/pvh/head.S
@@ -109,6 +109,10 @@ SYM_CODE_START_LOCAL(pvh_start_xen)
 	wrmsr
 
 #ifdef CONFIG_X86_PIE
+#ifdef CONFIG_PVM_GUEST
+	leaq	_text(%rip), %rdi
+	call	pvm_update_pgtable
+#endif
 	movabs  $2f, %rax
 	ANNOTATE_RETPOLINE_SAFE
 	jmp *%rax
-- 
2.19.1.6.gb485710b