linux-kernel - [PATCH v13 11/18] arm64: kexec: kexec may require EL2 vectors

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Date:   Thu,  8 Apr 2021 00:05:30 -0400
From:   Pavel Tatashin <pasha.tatashin@...een.com>
To:     pasha.tatashin@...een.com, jmorris@...ei.org, sashal@...nel.org,
        ebiederm@...ssion.com, kexec@...ts.infradead.org,
        linux-kernel@...r.kernel.org, corbet@....net,
        catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, maz@...nel.org,
        james.morse@....com, vladimir.murzin@....com,
        matthias.bgg@...il.com, linux-mm@...ck.org, mark.rutland@....com,
        steve.capper@....com, rfontana@...hat.com, tglx@...utronix.de,
        selindag@...il.com, tyhicks@...ux.microsoft.com,
        kernelfans@...il.com
Subject: [PATCH v13 11/18] arm64: kexec: kexec may require EL2 vectors

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 preporation to MMU enabled relocation, configure our EL2 table now.

Suggested-by: James Morse <james.morse@....com>
Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
---
 arch/arm64/Kconfig                |  2 +-
 arch/arm64/include/asm/kexec.h    |  1 +
 arch/arm64/kernel/asm-offsets.c   |  1 +
 arch/arm64/kernel/machine_kexec.c | 31 +++++++++++++++++++++++++++++++
 4 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e4e1b6550115..0e876d980a1f 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1149,7 +1149,7 @@ config CRASH_DUMP
 
 config TRANS_TABLE
 	def_bool y
-	depends on HIBERNATION
+	depends on HIBERNATION || KEXEC_CORE
 
 config XEN_DOM0
 	def_bool y
diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index 9befcd87e9a8..305cf0840ed3 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/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;
 	/* Core ELF header buffer */
 	void *elf_headers;
 	unsigned long elf_headers_mem;
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 0c92e193f866..2e3278df1fc3 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -157,6 +157,7 @@ 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();
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index 2e734e4ae12e..fb03b6676fb9 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -20,6 +20,7 @@
 #include <asm/mmu.h>
 #include <asm/mmu_context.h>
 #include <asm/page.h>
+#include <asm/trans_pgd.h>
 
 #include "cpu-reset.h"
 
@@ -42,7 +43,9 @@ 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",
@@ -137,9 +140,27 @@ 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) {
@@ -148,6 +169,14 @@ int machine_kexec_post_load(struct kimage *kimage)
 		return 0;
 	}
 
+	kimage->arch.el2_vectors = 0;
+	if (is_hyp_callable()) {
+		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);
@@ -200,6 +229,8 @@ void machine_kexec(struct kimage *kimage)
 		restart(is_hyp_callable(), kimage->start, kimage->arch.dtb_mem,
 			0, 0);
 	} else {
+		if (is_hyp_callable())
+			__hyp_set_vectors(kimage->arch.el2_vectors);
 		cpu_soft_restart(kimage->arch.kern_reloc, virt_to_phys(kimage),
 				 0, 0);
 	}
-- 
2.25.1