[PATCH v6 09/18] ACPI / APEI: Let the notification helper specify the fixmap slot

James Morse
2018-09-21T22:18:24Z

ghes_copy_tofrom_phys() uses a different fixmap slot depending on in_nmi().
This doesn't work when we have multiple NMI-like notifications, that
can interrupt each other.

As with the locking, move the chosen fixmap_idx to the notification helper.
This only matters for NMI-like notifications, anything calling
ghes_proc() can use the IRQ fixmap slot as its already holding an irqsave
spinlock.

This lets us collapse the ghes_ioremap_pfn_*() helpers.

Signed-off-by: James Morse <james.morse@arm.com>
---

The fixmap-idx and vaddr are passed back to ghes_unmap()
to allow ioremap() to be used in process context in the
future.
---
drivers/acpi/apei/ghes.c | 76 ++++++++++++++--------------------------
1 file changed, 27 insertions(+), 49 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index ed8669a6c100..adf7fd402813 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -41,6 +41,7 @@
#include <linux/llist.h>
#include <linux/genalloc.h>
#include <linux/pci.h>
+#include <linux/pfn.h>
#include <linux/aer.h>
#include <linux/nmi.h>
#include <linux/sched/clock.h>
@@ -129,38 +130,24 @@ static atomic_t ghes_estatus_cache_alloced;

static int ghes_panic_timeout __read_mostly = 30;

-static void __iomem *ghes_ioremap_pfn_nmi(u64 pfn)
+static void __iomem *ghes_map(u64 pfn, int fixmap_idx)
{
phys_addr_t paddr;
pgprot_t prot;

- paddr = pfn << PAGE_SHIFT;
+ paddr = PFN_PHYS(pfn);
prot = arch_apei_get_mem_attribute(paddr);
- __set_fixmap(FIX_APEI_GHES_NMI, paddr, prot);
+ __set_fixmap(fixmap_idx, paddr, prot);

- return (void __iomem *) fix_to_virt(FIX_APEI_GHES_NMI);
+ return (void __iomem *) __fix_to_virt(fixmap_idx);
}

-static void __iomem *ghes_ioremap_pfn_irq(u64 pfn)
+static void ghes_unmap(int fixmap_idx, void __iomem *vaddr)
{
- phys_addr_t paddr;
- pgprot_t prot;
-
- paddr = pfn << PAGE_SHIFT;
- prot = arch_apei_get_mem_attribute(paddr);
- __set_fixmap(FIX_APEI_GHES_IRQ, paddr, prot);
-
- return (void __iomem *) fix_to_virt(FIX_APEI_GHES_IRQ);
-}
-
-static void ghes_iounmap_nmi(void)
-{
- clear_fixmap(FIX_APEI_GHES_NMI);
-}
+ int _idx = virt_to_fix((unsigned long)vaddr);

-static void ghes_iounmap_irq(void)
-{
- clear_fixmap(FIX_APEI_GHES_IRQ);
+ WARN_ON_ONCE(fixmap_idx != _idx);
+ clear_fixmap(fixmap_idx);
}

static int ghes_estatus_pool_init(void)
@@ -289,20 +276,15 @@ static inline int ghes_severity(int severity)
}

static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len,
- int from_phys)
+ int from_phys, int fixmap_idx)
{
void __iomem *vaddr;
- int in_nmi = in_nmi();
u64 offset;
u32 trunk;

while (len > 0) {
offset = paddr - (paddr & PAGE_MASK);
- if (in_nmi) {
- vaddr = ghes_ioremap_pfn_nmi(paddr >> PAGE_SHIFT);
- } else {
- vaddr = ghes_ioremap_pfn_irq(paddr >> PAGE_SHIFT);
- }
+ vaddr = ghes_map(PHYS_PFN(paddr), fixmap_idx);
trunk = PAGE_SIZE - offset;
trunk = min(trunk, len);
if (from_phys)
@@ -312,15 +294,11 @@ static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len,
len -= trunk;
paddr += trunk;
buffer += trunk;
- if (in_nmi) {
- ghes_iounmap_nmi();
- } else {
- ghes_iounmap_irq();
- }
+ ghes_unmap(fixmap_idx, vaddr);
}
}

-static int ghes_read_estatus(struct ghes *ghes, int silent)
+static int ghes_read_estatus(struct ghes *ghes, int silent, int fixmap_idx)
{
struct acpi_hest_generic *g = ghes->generic;
u64 buf_paddr;
@@ -339,7 +317,7 @@ static int ghes_read_estatus(struct ghes *ghes, int silent)
return -ENOENT;

ghes_copy_tofrom_phys(ghes->estatus, buf_paddr,
- sizeof(*ghes->estatus), 1);
+ sizeof(*ghes->estatus), 1, fixmap_idx);
if (!ghes->estatus->block_status)
return -ENOENT;

@@ -356,7 +334,7 @@ static int ghes_read_estatus(struct ghes *ghes, int silent)
goto err_read_block;
ghes_copy_tofrom_phys(ghes->estatus + 1,
buf_paddr + sizeof(*ghes->estatus),
- len - sizeof(*ghes->estatus), 1);
+ len - sizeof(*ghes->estatus), 1, fixmap_idx);
if (cper_estatus_check(ghes->estatus))
goto err_read_block;
rc = 0;
@@ -368,13 +346,13 @@ static int ghes_read_estatus(struct ghes *ghes, int silent)
return rc;
}

-static void ghes_clear_estatus(struct ghes *ghes)
+static void ghes_clear_estatus(struct ghes *ghes, int fixmap_idx)
{
ghes->estatus->block_status = 0;
if (!(ghes->flags & GHES_TO_CLEAR))
return;
ghes_copy_tofrom_phys(ghes->estatus, ghes->buffer_paddr,
- sizeof(ghes->estatus->block_status), 0);
+ sizeof(ghes->estatus->block_status), 0, fixmap_idx);
ghes->flags &= ~GHES_TO_CLEAR;
}

@@ -740,12 +718,12 @@ static void __process_error(struct ghes *ghes)
llist_add(&estatus_node->llnode, &ghes_estatus_llist);
}

-static int _in_nmi_notify_one(struct ghes *ghes)
+static int _in_nmi_notify_one(struct ghes *ghes, int fixmap_idx)
{
int sev;

- if (ghes_read_estatus(ghes, 1)) {
- ghes_clear_estatus(ghes);
+ if (ghes_read_estatus(ghes, 1, fixmap_idx)) {
+ ghes_clear_estatus(ghes, fixmap_idx);
return -ENOENT;
}

@@ -759,19 +737,19 @@ static int _in_nmi_notify_one(struct ghes *ghes)
return 0;

__process_error(ghes);
- ghes_clear_estatus(ghes);
+ ghes_clear_estatus(ghes, fixmap_idx);

return 0;
}

-static int ghes_estatus_queue_notified(struct list_head *rcu_list)
+static int ghes_estatus_queue_notified(struct list_head *rcu_list, int fixmap_idx)
{
int ret = -ENOENT;
struct ghes *ghes;

rcu_read_lock();
list_for_each_entry_rcu(ghes, rcu_list, list) {
- if (!_in_nmi_notify_one(ghes))
+ if (!_in_nmi_notify_one(ghes, fixmap_idx))
ret = 0;
}
rcu_read_unlock();
@@ -876,7 +854,7 @@ static int ghes_proc(struct ghes *ghes)
{
int rc;

- rc = ghes_read_estatus(ghes, 0);
+ rc = ghes_read_estatus(ghes, 0, FIX_APEI_GHES_IRQ);
if (rc)
goto out;

@@ -891,7 +869,7 @@ static int ghes_proc(struct ghes *ghes)
ghes_do_proc(ghes, ghes->estatus);

out:
- ghes_clear_estatus(ghes);
+ ghes_clear_estatus(ghes, FIX_APEI_GHES_IRQ);

if (rc == -ENOENT)
return rc;
@@ -984,7 +962,7 @@ int ghes_notify_sea(void)
int rv;

raw_spin_lock(&ghes_notify_lock_sea);
- rv = ghes_estatus_queue_notified(&ghes_sea);
+ rv = ghes_estatus_queue_notified(&ghes_sea, FIX_APEI_GHES_NMI);
raw_spin_unlock(&ghes_notify_lock_sea);

return rv;
@@ -1031,7 +1009,7 @@ static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
return ret;

raw_spin_lock(&ghes_notify_lock_nmi);
- if (!ghes_estatus_queue_notified(&ghes_nmi))
+ if (!ghes_estatus_queue_notified(&ghes_nmi, FIX_APEI_GHES_NMI))
ret = NMI_HANDLED;
raw_spin_unlock(&ghes_notify_lock_nmi);

--
2.19.0