[PATCH v15 08/15] arm64: kexec: configure EL2 vectors for kexec

From: Pavel Tatashin
Date: Tue Jun 08 2021 - 20:45:47 EST


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: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
---
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 +++++++++++++++++++++++++++++++
arch/arm64/mm/trans_pgd-asm.S | 9 ++++++++-
5 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 9f1d8566bbf9..e775e6fb03c5 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1148,7 +1148,7 @@ 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 00dbcc71aeb2..753a1c398898 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;
};

#ifdef CONFIG_KEXEC_FILE
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 92c2ed846730..ee37d0e0fb6d 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -159,6 +159,7 @@ 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 e88d5cfbef40..e0ef88cc57d2 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_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);
@@ -200,6 +229,8 @@ 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);
}
diff --git a/arch/arm64/mm/trans_pgd-asm.S b/arch/arm64/mm/trans_pgd-asm.S
index 831d6369494e..c1f2ed1be6de 100644
--- a/arch/arm64/mm/trans_pgd-asm.S
+++ b/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)
--
2.25.1