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FROMLIST: KVM: arm64: Add trace interface for hyp tracefs

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The trace interface is solely here to reset tracing. Non-consuming read
is not yet supported due to the lack of support in the ring-buffer
meta page.

Bug: 357781595
Link: https://lore.kernel.org/all/20240911093029.3279154-12-vdonnefort@google.com/
Change-Id: Ib8a28f7b46efee53c6caab753ce578c9411a358d
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
This commit is contained in:
Vincent Donnefort
2024-09-09 08:23:46 +01:00
committed by Keir Fraser
parent 532d6ef155
commit a368d579d1
5 changed files with 123 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
arch/arm64/include/asm/kvm_asm.h
+1
View File
@@ -89,6 +89,7 @@ enum __kvm_host_smccc_func {
__KVM_HOST_SMCCC_FUNC___pkvm_load_tracing,
__KVM_HOST_SMCCC_FUNC___pkvm_teardown_tracing,
__KVM_HOST_SMCCC_FUNC___pkvm_enable_tracing,
__KVM_HOST_SMCCC_FUNC___pkvm_reset_tracing,
__KVM_HOST_SMCCC_FUNC___pkvm_swap_reader_tracing,
};
arch/arm64/kvm/hyp/include/nvhe/trace.h
+2
View File
@@ -20,6 +20,7 @@ void __pkvm_update_clock_tracing(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_cy
int __pkvm_load_tracing(unsigned long desc_va, size_t desc_size);
void __pkvm_teardown_tracing(void);
int __pkvm_enable_tracing(bool enable);
int __pkvm_reset_tracing(unsigned int cpu);
int __pkvm_swap_reader_tracing(unsigned int cpu);
#else
static inline void *tracing_reserve_entry(unsigned long length) { return NULL; }
@@ -30,6 +31,7 @@ void __pkvm_update_clock_tracing(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_cy
static inline int __pkvm_load_tracing(unsigned long desc_va, size_t desc_size) { return -ENODEV; }
static inline void __pkvm_teardown_tracing(void) { }
static inline int __pkvm_enable_tracing(bool enable) { return -ENODEV; }
static inline int __pkvm_reset_tracing(unsigned int cpu) { return -ENODEV; }
static inline int __pkvm_swap_reader_tracing(unsigned int cpu) { return -ENODEV; }
#endif
#endif
arch/arm64/kvm/hyp/nvhe/hyp-main.c
+8
View File
@@ -1243,6 +1243,13 @@ static void handle___pkvm_enable_tracing(struct kvm_cpu_context *host_ctxt)
cpu_reg(host_ctxt, 1) = __pkvm_enable_tracing(enable);
}
static void handle___pkvm_reset_tracing(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(unsigned int, cpu, host_ctxt, 1);
cpu_reg(host_ctxt, 1) = __pkvm_reset_tracing(cpu);
}
static void handle___pkvm_swap_reader_tracing(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(unsigned int, cpu, host_ctxt, 1);
@@ -1291,6 +1298,7 @@ static const hcall_t host_hcall[] = {
HANDLE_FUNC(__pkvm_load_tracing),
HANDLE_FUNC(__pkvm_teardown_tracing),
HANDLE_FUNC(__pkvm_enable_tracing),
HANDLE_FUNC(__pkvm_reset_tracing),
HANDLE_FUNC(__pkvm_swap_reader_tracing),
};
arch/arm64/kvm/hyp/nvhe/trace.c
+57 -1
View File
@@ -284,12 +284,20 @@ static int rb_page_init(struct hyp_buffer_page *bpage, unsigned long hva)
return 0;
}
static void rb_page_reset(struct hyp_buffer_page *bpage)
{
bpage->write = 0;
bpage->entries = 0;
local_set(&bpage->page->commit, 0);
}
static bool rb_cpu_loaded(struct hyp_rb_per_cpu *cpu_buffer)
{
return !!cpu_buffer->bpages;
}
static void rb_cpu_disable_writing(struct hyp_rb_per_cpu *cpu_buffer)
static int rb_cpu_disable_writing(struct hyp_rb_per_cpu *cpu_buffer)
{
int prev_status;
@@ -299,6 +307,8 @@ static void rb_cpu_disable_writing(struct hyp_rb_per_cpu *cpu_buffer)
HYP_RB_READY,
HYP_RB_UNAVAILABLE);
} while (prev_status == HYP_RB_WRITING);
return prev_status;
}
static int rb_cpu_enable_writing(struct hyp_rb_per_cpu *cpu_buffer)
@@ -311,6 +321,38 @@ static int rb_cpu_enable_writing(struct hyp_rb_per_cpu *cpu_buffer)
return 0;
}
static int rb_cpu_reset(struct hyp_rb_per_cpu *cpu_buffer)
{
struct hyp_buffer_page *bpage;
int prev_status;
if (!rb_cpu_loaded(cpu_buffer))
return -ENODEV;
prev_status = rb_cpu_disable_writing(cpu_buffer);
bpage = cpu_buffer->head_page;
do {
rb_page_reset(bpage);
bpage = rb_next_page(bpage);
} while (bpage != cpu_buffer->head_page);
rb_page_reset(cpu_buffer->reader_page);
cpu_buffer->meta->reader.read = 0;
cpu_buffer->meta->reader.lost_events = 0;
cpu_buffer->meta->entries = 0;
cpu_buffer->meta->overrun = 0;
cpu_buffer->meta->read = 0;
meta_pages_lost(cpu_buffer->meta) = 0;
meta_pages_touched(cpu_buffer->meta) = 0;
if (prev_status == HYP_RB_READY)
rb_cpu_enable_writing(cpu_buffer);
return 0;
}
static void rb_cpu_teardown(struct hyp_rb_per_cpu *cpu_buffer)
{
int i;
@@ -602,3 +644,17 @@ int __pkvm_enable_tracing(bool enable)
return ret;
}
int __pkvm_reset_tracing(unsigned int cpu)
{
int ret = 0;
if (cpu >= hyp_nr_cpus)
return -EINVAL;
hyp_spin_lock(&trace_rb_lock);
ret = rb_cpu_reset(per_cpu_ptr(&trace_rb, cpu));
hyp_spin_unlock(&trace_rb_lock);
return ret;
}
arch/arm64/kvm/hyp_trace.c
+55
View File
@@ -196,6 +196,11 @@ static int __get_reader_page(int cpu)
return kvm_call_hyp_nvhe(__pkvm_swap_reader_tracing, cpu);
}
static int __reset(int cpu)
{
return kvm_call_hyp_nvhe(__pkvm_reset_tracing, cpu);
}
static void hyp_trace_free_pages(struct hyp_trace_desc *desc)
{
struct rb_page_desc *rb_desc;
@@ -354,6 +359,7 @@ static int hyp_trace_buffer_load(struct hyp_trace_buffer *hyp_buffer, size_t siz
hyp_buffer->writer.pdesc = &desc->page_desc;
hyp_buffer->writer.get_reader_page = __get_reader_page;
hyp_buffer->writer.reset = __reset;
hyp_buffer->trace_buffer = ring_buffer_reader(&hyp_buffer->writer);
if (!hyp_buffer->trace_buffer) {
ret = -ENOMEM;
@@ -818,6 +824,49 @@ static const struct file_operations hyp_trace_raw_fops = {
.release = hyp_trace_raw_release,
};
static void hyp_trace_reset(int cpu)
{
struct hyp_trace_buffer *hyp_buffer = &hyp_trace_buffer;
mutex_lock(&hyp_buffer->lock);
if (!hyp_trace_buffer_loaded(hyp_buffer))
goto out;
if (cpu == RING_BUFFER_ALL_CPUS)
ring_buffer_reset(hyp_buffer->trace_buffer);
else
ring_buffer_reset_cpu(hyp_buffer->trace_buffer, cpu);
out:
mutex_unlock(&hyp_buffer->lock);
}
static int hyp_trace_open(struct inode *inode, struct file *file)
{
int cpu = (s64)inode->i_private;
if (file->f_mode & FMODE_WRITE) {
hyp_trace_reset(cpu);
return 0;
}
return -EPERM;
}
static ssize_t hyp_trace_write(struct file *filp, const char __user *ubuf,
size_t count, loff_t *ppos)
{
return count;
}
static const struct file_operations hyp_trace_fops = {
.open = hyp_trace_open,
.write = hyp_trace_write,
.release = NULL,
};
static int hyp_trace_clock_show(struct seq_file *m, void *v)
{
seq_puts(m, "[boot]\n");
@@ -850,6 +899,9 @@ int hyp_trace_init_tracefs(void)
tracefs_create_file("trace_pipe", TRACEFS_MODE_WRITE, root,
(void *)RING_BUFFER_ALL_CPUS, &hyp_trace_pipe_fops);
tracefs_create_file("trace", TRACEFS_MODE_WRITE, root,
(void *)RING_BUFFER_ALL_CPUS, &hyp_trace_fops);
tracefs_create_file("trace_clock", TRACEFS_MODE_READ, root, NULL,
&hyp_trace_clock_fops);
@@ -875,6 +927,9 @@ int hyp_trace_init_tracefs(void)
tracefs_create_file("trace_pipe_raw", TRACEFS_MODE_READ, per_cpu_dir,
(void *)cpu, &hyp_trace_pipe_fops);
tracefs_create_file("trace", TRACEFS_MODE_READ, per_cpu_dir,
(void *)cpu, &hyp_trace_fops);
}
return 0;