arm64: kexec: configure EL2 vectors for kexec

If we have a EL2 mode without VHE, the EL2 vectors are needed in order
to switch to EL2 and jump to new world with hypervisor privileges.

In preparation to MMU enabled relocation, configure our EL2 table now.

Kexec uses #HVC_SOFT_RESTART to branch to the new world, so extend
el1_sync vector that is provided by trans_pgd_copy_el2_vectors() to
support this case.

Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210930143113.1502553-9-pasha.tatashin@soleen.com
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/Kconfig

@@ -1135,7 +1135,7 @@ config CRASH_DUMP
 
 config TRANS_TABLE
 	def_bool y
-	depends on HIBERNATION
+	depends on HIBERNATION || KEXEC_CORE
 
 config XEN_DOM0
 	def_bool y

arch/arm64/include/asm/kexec.h

@@ -96,6 +96,7 @@ struct kimage_arch {
 	void *dtb;
 	phys_addr_t dtb_mem;
 	phys_addr_t kern_reloc;
+	phys_addr_t el2_vectors;
 };
 
 #ifdef CONFIG_KEXEC_FILE

arch/arm64/kernel/asm-offsets.c

@@ -174,6 +174,7 @@ int main(void)
 #endif
 #ifdef CONFIG_KEXEC_CORE
   DEFINE(KIMAGE_ARCH_DTB_MEM,		offsetof(struct kimage, arch.dtb_mem));
+  DEFINE(KIMAGE_ARCH_EL2_VECTORS,	offsetof(struct kimage, arch.el2_vectors));
   DEFINE(KIMAGE_HEAD,			offsetof(struct kimage, head));
   DEFINE(KIMAGE_START,			offsetof(struct kimage, start));
   BLANK();

arch/arm64/kernel/machine_kexec.c

@@ -21,6 +21,7 @@
 #include <asm/mmu.h>
 #include <asm/mmu_context.h>
 #include <asm/page.h>
+#include <asm/trans_pgd.h>
 
 #include "cpu-reset.h"
 
@@ -43,7 +44,9 @@ static void _kexec_image_info(const char *func, int line,
 	pr_debug("    start:       %lx\n", kimage->start);
 	pr_debug("    head:        %lx\n", kimage->head);
 	pr_debug("    nr_segments: %lu\n", kimage->nr_segments);
+	pr_debug("    dtb_mem: %pa\n", &kimage->arch.dtb_mem);
 	pr_debug("    kern_reloc: %pa\n", &kimage->arch.kern_reloc);
+	pr_debug("    el2_vectors: %pa\n", &kimage->arch.el2_vectors);
 
 	for (i = 0; i < kimage->nr_segments; i++) {
 		pr_debug("      segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu pages\n",
@@ -143,9 +146,27 @@ static void kexec_segment_flush(const struct kimage *kimage)
 	}
 }
 
+/* Allocates pages for kexec page table */
+static void *kexec_page_alloc(void *arg)
+{
+	struct kimage *kimage = (struct kimage *)arg;
+	struct page *page = kimage_alloc_control_pages(kimage, 0);
+
+	if (!page)
+		return NULL;
+
+	memset(page_address(page), 0, PAGE_SIZE);
+
+	return page_address(page);
+}
+
 int machine_kexec_post_load(struct kimage *kimage)
 {
 	void *reloc_code = page_to_virt(kimage->control_code_page);
+	struct trans_pgd_info info = {
+		.trans_alloc_page	= kexec_page_alloc,
+		.trans_alloc_arg	= kimage,
+	};
 
 	/* If in place, relocation is not used, only flush next kernel */
 	if (kimage->head & IND_DONE) {
@@ -154,6 +175,14 @@ int machine_kexec_post_load(struct kimage *kimage)
 		return 0;
 	}
 
+	kimage->arch.el2_vectors = 0;
+	if (is_hyp_nvhe()) {
+		int rc = trans_pgd_copy_el2_vectors(&info,
+						    &kimage->arch.el2_vectors);
+		if (rc)
+			return rc;
+	}
+
 	memcpy(reloc_code, arm64_relocate_new_kernel,
 	       arm64_relocate_new_kernel_size);
 	kimage->arch.kern_reloc = __pa(reloc_code);
@@ -209,6 +238,8 @@ void machine_kexec(struct kimage *kimage)
 		restart(is_hyp_nvhe(), kimage->start, kimage->arch.dtb_mem,
 			0, 0);
 	} else {
+		if (is_hyp_nvhe())
+			__hyp_set_vectors(kimage->arch.el2_vectors);
 		cpu_soft_restart(kimage->arch.kern_reloc, virt_to_phys(kimage),
 				 0, 0);
 	}

arch/arm64/mm/trans_pgd-asm.S

@@ -24,7 +24,14 @@ SYM_CODE_START_LOCAL(el1_sync)
 	msr	vbar_el2, x1
 	mov	x0, xzr
 	eret
-1:	/* Unexpected argument, set an error */
+1:	cmp	x0, #HVC_SOFT_RESTART	/* Called from kexec */
+	b.ne	2f
+	mov	x0, x2
+	mov	x2, x4
+	mov	x4, x1
+	mov	x1, x3
+	br	x4
+2:	/* Unexpected argument, set an error */
 	mov_q	x0, HVC_STUB_ERR
 	eret
 SYM_CODE_END(el1_sync)