[PATCH] arm64: kvm: Make nvhe stack size configurable
From: Kalesh Singh
Date: Fri Nov 08 2024 - 16:15:45 EST
In order to make the nVHE stack size easily configurable,
introduce NVHE_STACK_SHIFT which must be >= PAGE_SHIFT.
The default stack size remains 1 page (no functional change)
Downstream vendor features which require a larger stack
can configure it by setting CONFIG_NVHE_STACK_SHIFT.
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Quentin Perret <qperret@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
---
arch/arm64/include/asm/memory.h | 5 ++++-
arch/arm64/include/asm/stacktrace/nvhe.h | 2 +-
arch/arm64/kvm/Kconfig | 14 ++++++++++++++
arch/arm64/kvm/arm.c | 18 +++++++++---------
arch/arm64/kvm/hyp/nvhe/host.S | 4 ++--
arch/arm64/kvm/hyp/nvhe/mm.c | 12 ++++++------
arch/arm64/kvm/hyp/nvhe/stacktrace.c | 4 ++--
arch/arm64/kvm/mmu.c | 12 ++++++------
arch/arm64/kvm/stacktrace.c | 6 +++---
9 files changed, 47 insertions(+), 30 deletions(-)
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 0480c61dbb4f..55e592351749 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -145,13 +145,16 @@
#define OVERFLOW_STACK_SIZE SZ_4K
+#define NVHE_STACK_SHIFT CONFIG_NVHE_STACK_SHIFT
+#define NVHE_STACK_SIZE (UL(1) << NVHE_STACK_SHIFT)
+
/*
* With the minimum frame size of [x29, x30], exactly half the combined
* sizes of the hyp and overflow stacks is the maximum size needed to
* save the unwinded stacktrace; plus an additional entry to delimit the
* end.
*/
-#define NVHE_STACKTRACE_SIZE ((OVERFLOW_STACK_SIZE + PAGE_SIZE) / 2 + sizeof(long))
+#define NVHE_STACKTRACE_SIZE ((OVERFLOW_STACK_SIZE + NVHE_STACK_SIZE) / 2 + sizeof(long))
/*
* Alignment of kernel segments (e.g. .text, .data).
diff --git a/arch/arm64/include/asm/stacktrace/nvhe.h b/arch/arm64/include/asm/stacktrace/nvhe.h
index 44759281d0d4..171f9edef49f 100644
--- a/arch/arm64/include/asm/stacktrace/nvhe.h
+++ b/arch/arm64/include/asm/stacktrace/nvhe.h
@@ -47,7 +47,7 @@ static inline void kvm_nvhe_unwind_init(struct unwind_state *state,
DECLARE_KVM_NVHE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);
DECLARE_KVM_NVHE_PER_CPU(struct kvm_nvhe_stacktrace_info, kvm_stacktrace_info);
-DECLARE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
+DECLARE_PER_CPU(unsigned long, kvm_arm_hyp_stack_base);
void kvm_nvhe_dump_backtrace(unsigned long hyp_offset);
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index ead632ad01b4..7aaf0951086c 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -66,6 +66,20 @@ config PROTECTED_NVHE_STACKTRACE
If unsure, or not using protected nVHE (pKVM), say N.
+config NVHE_STACK_SHIFT
+ int "Size of the nVHE stack as a power of 2"
+ depends on KVM
+ range 12 13 if ARM64_4K_PAGES
+ default "12" if ARM64_4K_PAGES
+ range 14 15 if ARM64_16K_PAGES
+ default "14" if ARM64_16K_PAGES
+ range 16 17 if ARM64_64K_PAGES
+ default "16" if ARM64_64K_PAGES
+ help
+ This option specifies the size of the KVM nVHE stack (for both
+ conventional nVHE and pKVM modes) as a power of 2 -- which must
+ be at least as large as PAGE_SIZE.
+
config PTDUMP_STAGE2_DEBUGFS
bool "Present the stage-2 pagetables to debugfs"
depends on KVM
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 48cafb65d6ac..d19bffbfcb9e 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -61,7 +61,7 @@ static enum kvm_wfx_trap_policy kvm_wfe_trap_policy __read_mostly = KVM_WFX_NOTR
DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector);
-DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
+DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_base);
DECLARE_KVM_NVHE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
DECLARE_KVM_NVHE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
@@ -2359,7 +2359,7 @@ static void __init teardown_hyp_mode(void)
free_hyp_pgds();
for_each_possible_cpu(cpu) {
- free_page(per_cpu(kvm_arm_hyp_stack_page, cpu));
+ free_pages(per_cpu(kvm_arm_hyp_stack_base, cpu), NVHE_STACK_SHIFT - PAGE_SHIFT);
free_pages(kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu], nvhe_percpu_order());
if (free_sve) {
@@ -2547,15 +2547,15 @@ static int __init init_hyp_mode(void)
* Allocate stack pages for Hypervisor-mode
*/
for_each_possible_cpu(cpu) {
- unsigned long stack_page;
+ unsigned long stack_base;
- stack_page = __get_free_page(GFP_KERNEL);
- if (!stack_page) {
+ stack_base = __get_free_pages(GFP_KERNEL, NVHE_STACK_SHIFT - PAGE_SHIFT);
+ if (!stack_base) {
err = -ENOMEM;
goto out_err;
}
- per_cpu(kvm_arm_hyp_stack_page, cpu) = stack_page;
+ per_cpu(kvm_arm_hyp_stack_base, cpu) = stack_base;
}
/*
@@ -2624,9 +2624,9 @@ static int __init init_hyp_mode(void)
*/
for_each_possible_cpu(cpu) {
struct kvm_nvhe_init_params *params = per_cpu_ptr_nvhe_sym(kvm_init_params, cpu);
- char *stack_page = (char *)per_cpu(kvm_arm_hyp_stack_page, cpu);
+ char *stack_base = (char *)per_cpu(kvm_arm_hyp_stack_base, cpu);
- err = create_hyp_stack(__pa(stack_page), ¶ms->stack_hyp_va);
+ err = create_hyp_stack(__pa(stack_base), ¶ms->stack_hyp_va);
if (err) {
kvm_err("Cannot map hyp stack\n");
goto out_err;
@@ -2638,7 +2638,7 @@ static int __init init_hyp_mode(void)
* __hyp_pa() won't do the right thing there, since the stack
* has been mapped in the flexible private VA space.
*/
- params->stack_pa = __pa(stack_page);
+ params->stack_pa = __pa(stack_base);
}
for_each_possible_cpu(cpu) {
diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index 3d610fc51f4d..58f0cb2298cc 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -188,12 +188,12 @@ SYM_FUNC_END(__host_hvc)
/*
* Test whether the SP has overflowed, without corrupting a GPR.
- * nVHE hypervisor stacks are aligned so that the PAGE_SHIFT bit
+ * nVHE hypervisor stacks are aligned so that the NVHE_STACK_SHIFT bit
* of SP should always be 1.
*/
add sp, sp, x0 // sp' = sp + x0
sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp
- tbz x0, #PAGE_SHIFT, .L__hyp_sp_overflow\@
+ tbz x0, #NVHE_STACK_SHIFT, .L__hyp_sp_overflow\@
sub x0, sp, x0 // x0'' = sp' - x0' = (sp + x0) - sp = x0
sub sp, sp, x0 // sp'' = sp' - x0 = (sp + x0) - x0 = sp
diff --git a/arch/arm64/kvm/hyp/nvhe/mm.c b/arch/arm64/kvm/hyp/nvhe/mm.c
index 8850b591d775..f41c7440b34b 100644
--- a/arch/arm64/kvm/hyp/nvhe/mm.c
+++ b/arch/arm64/kvm/hyp/nvhe/mm.c
@@ -360,10 +360,10 @@ int pkvm_create_stack(phys_addr_t phys, unsigned long *haddr)
prev_base = __io_map_base;
/*
- * Efficient stack verification using the PAGE_SHIFT bit implies
+ * Efficient stack verification using the NVHE_STACK_SHIFT bit implies
* an alignment of our allocation on the order of the size.
*/
- size = PAGE_SIZE * 2;
+ size = NVHE_STACK_SIZE * 2;
addr = ALIGN(__io_map_base, size);
ret = __pkvm_alloc_private_va_range(addr, size);
@@ -373,12 +373,12 @@ int pkvm_create_stack(phys_addr_t phys, unsigned long *haddr)
* at the higher address and leave the lower guard page
* unbacked.
*
- * Any valid stack address now has the PAGE_SHIFT bit as 1
+ * Any valid stack address now has the NVHE_STACK_SHIFT bit as 1
* and addresses corresponding to the guard page have the
- * PAGE_SHIFT bit as 0 - this is used for overflow detection.
+ * NVHE_STACK_SHIFT bit as 0 - this is used for overflow detection.
*/
- ret = kvm_pgtable_hyp_map(&pkvm_pgtable, addr + PAGE_SIZE,
- PAGE_SIZE, phys, PAGE_HYP);
+ ret = kvm_pgtable_hyp_map(&pkvm_pgtable, addr + NVHE_STACK_SIZE,
+ NVHE_STACK_SIZE, phys, PAGE_HYP);
if (ret)
__io_map_base = prev_base;
}
diff --git a/arch/arm64/kvm/hyp/nvhe/stacktrace.c b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
index ed6b58b19cfa..5b6eeab1a774 100644
--- a/arch/arm64/kvm/hyp/nvhe/stacktrace.c
+++ b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
@@ -28,7 +28,7 @@ static void hyp_prepare_backtrace(unsigned long fp, unsigned long pc)
struct kvm_nvhe_stacktrace_info *stacktrace_info = this_cpu_ptr(&kvm_stacktrace_info);
struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
- stacktrace_info->stack_base = (unsigned long)(params->stack_hyp_va - PAGE_SIZE);
+ stacktrace_info->stack_base = (unsigned long)(params->stack_hyp_va - NVHE_STACK_SIZE);
stacktrace_info->overflow_stack_base = (unsigned long)this_cpu_ptr(overflow_stack);
stacktrace_info->fp = fp;
stacktrace_info->pc = pc;
@@ -54,7 +54,7 @@ static struct stack_info stackinfo_get_hyp(void)
{
struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
unsigned long high = params->stack_hyp_va;
- unsigned long low = high - PAGE_SIZE;
+ unsigned long low = high - NVHE_STACK_SIZE;
return (struct stack_info) {
.low = low,
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 0f7658aefa1a..e366ed8650fe 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -704,10 +704,10 @@ int create_hyp_stack(phys_addr_t phys_addr, unsigned long *haddr)
mutex_lock(&kvm_hyp_pgd_mutex);
/*
- * Efficient stack verification using the PAGE_SHIFT bit implies
+ * Efficient stack verification using the NVHE_STACK_SHIFT bit implies
* an alignment of our allocation on the order of the size.
*/
- size = PAGE_SIZE * 2;
+ size = NVHE_STACK_SIZE * 2;
base = ALIGN_DOWN(io_map_base - size, size);
ret = __hyp_alloc_private_va_range(base);
@@ -724,12 +724,12 @@ int create_hyp_stack(phys_addr_t phys_addr, unsigned long *haddr)
* at the higher address and leave the lower guard page
* unbacked.
*
- * Any valid stack address now has the PAGE_SHIFT bit as 1
+ * Any valid stack address now has the NVHE_STACK_SHIFT bit as 1
* and addresses corresponding to the guard page have the
- * PAGE_SHIFT bit as 0 - this is used for overflow detection.
+ * NVHE_STACK_SHIFT bit as 0 - this is used for overflow detection.
*/
- ret = __create_hyp_mappings(base + PAGE_SIZE, PAGE_SIZE, phys_addr,
- PAGE_HYP);
+ ret = __create_hyp_mappings(base + NVHE_STACK_SIZE, NVHE_STACK_SIZE,
+ phys_addr, PAGE_HYP);
if (ret)
kvm_err("Cannot map hyp stack\n");
diff --git a/arch/arm64/kvm/stacktrace.c b/arch/arm64/kvm/stacktrace.c
index 3ace5b75813b..b9744a932920 100644
--- a/arch/arm64/kvm/stacktrace.c
+++ b/arch/arm64/kvm/stacktrace.c
@@ -50,7 +50,7 @@ static struct stack_info stackinfo_get_hyp(void)
struct kvm_nvhe_stacktrace_info *stacktrace_info
= this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
unsigned long low = (unsigned long)stacktrace_info->stack_base;
- unsigned long high = low + PAGE_SIZE;
+ unsigned long high = low + NVHE_STACK_SIZE;
return (struct stack_info) {
.low = low,
@@ -60,8 +60,8 @@ static struct stack_info stackinfo_get_hyp(void)
static struct stack_info stackinfo_get_hyp_kern_va(void)
{
- unsigned long low = (unsigned long)*this_cpu_ptr(&kvm_arm_hyp_stack_page);
- unsigned long high = low + PAGE_SIZE;
+ unsigned long low = (unsigned long)*this_cpu_ptr(&kvm_arm_hyp_stack_base);
+ unsigned long high = low + NVHE_STACK_SIZE;
return (struct stack_info) {
.low = low,
--
2.47.0.277.g8800431eea-goog