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arm64: KVM/mm: Move SEA handling behind a single 'claim' interface

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To split up APEIs in_nmi() path, the caller needs to always be
in_nmi(). Add a helper to do the work and claim the notification.

When KVM or the arch code takes an exception that might be a RAS
notification, it asks the APEI firmware-first code whether it wants
to claim the exception. A future kernel-first mechanism may be queried
afterwards, and claim the notification, otherwise we fall through
to the existing default behaviour.

The NOTIFY_SEA code was merged before considering multiple, possibly
interacting, NMI-like notifications and the need to consider kernel
first in the future. Make the 'claiming' behaviour explicit.

Restructuring the APEI code to allow multiple NMI-like notifications
means any notification that might interrupt interrupts-masked
code must always be wrapped in nmi_enter()/nmi_exit(). This will
allow APEI to use in_nmi() to use the right fixmap entries.

Mask SError over this window to prevent an asynchronous RAS error
arriving and tripping 'nmi_enter()'s BUG_ON(in_nmi()).

Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Tested-by: Tyler Baicar <tbaicar@codeaurora.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
James Morse 2019-01-29 18:48:50 +00:00 committed by Rafael J. Wysocki
parent 0db5e02230
commit d44f1b8dd7
5 changed files with 55 additions and 21 deletions
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4
arch/arm64/include/asm/acpi.h
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@ -18,6 +18,7 @@
#include <asm/cputype.h>
#include <asm/io.h>
#include <asm/ptrace.h>
#include <asm/smp_plat.h>
#include <asm/tlbflush.h>
@ -110,9 +111,10 @@ static inline u32 get_acpi_id_for_cpu(unsigned int cpu)
static inline void arch_fix_phys_package_id(int num, u32 slot) { }
void __init acpi_init_cpus(void);
int apei_claim_sea(struct pt_regs *regs);
#else
static inline void acpi_init_cpus(void) { }
static inline int apei_claim_sea(struct pt_regs *regs) { return -ENOENT; }
#endif /* CONFIG_ACPI */
#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL

1
arch/arm64/include/asm/daifflags.h
View File

@ -20,6 +20,7 @@
#define DAIF_PROCCTX 0
#define DAIF_PROCCTX_NOIRQ PSR_I_BIT
#define DAIF_ERRCTX (PSR_I_BIT | PSR_A_BIT)
/* mask/save/unmask/restore all exceptions, including interrupts. */
static inline void local_daif_mask(void)

16
arch/arm64/include/asm/kvm_ras.h
View File

@ -4,8 +4,22 @@
#ifndef __ARM64_KVM_RAS_H__
#define __ARM64_KVM_RAS_H__
#include <linux/acpi.h>
#include <linux/errno.h>
#include <linux/types.h>
int kvm_handle_guest_sea(phys_addr_t addr, unsigned int esr);
#include <asm/acpi.h>
/*
* Was this synchronous external abort a RAS notification?
* Returns '0' for errors handled by some RAS subsystem, or -ENOENT.
*/
static inline int kvm_handle_guest_sea(phys_addr_t addr, unsigned int esr)
{
/* apei_claim_sea(NULL) expects to mask interrupts itself */
lockdep_assert_irqs_enabled();
return apei_claim_sea(NULL);
}
#endif /* __ARM64_KVM_RAS_H__ */

31
arch/arm64/kernel/acpi.c
View File

@ -27,8 +27,10 @@
#include <linux/smp.h>
#include <linux/serial_core.h>
#include <acpi/ghes.h>
#include <asm/cputype.h>
#include <asm/cpu_ops.h>
#include <asm/daifflags.h>
#include <asm/pgtable.h>
#include <asm/smp_plat.h>
@ -256,3 +258,32 @@ pgprot_t __acpi_get_mem_attribute(phys_addr_t addr)
return __pgprot(PROT_NORMAL_NC);
return __pgprot(PROT_DEVICE_nGnRnE);
}
/*
* Claim Synchronous External Aborts as a firmware first notification.
*
* Used by KVM and the arch do_sea handler.
* @regs may be NULL when called from process context.
*/
int apei_claim_sea(struct pt_regs *regs)
{
int err = -ENOENT;
unsigned long current_flags;
if (!IS_ENABLED(CONFIG_ACPI_APEI_GHES))
return err;
current_flags = arch_local_save_flags();
/*
* SEA can interrupt SError, mask it and describe this as an NMI so
* that APEI defers the handling.
*/
local_daif_restore(DAIF_ERRCTX);
nmi_enter();
err = ghes_notify_sea();
nmi_exit();
local_daif_restore(current_flags);
return err;
}

24
arch/arm64/mm/fault.c
View File

@ -18,6 +18,7 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/acpi.h>
#include <linux/extable.h>
#include <linux/signal.h>
#include <linux/mm.h>
@ -33,6 +34,7 @@
#include <linux/preempt.h>
#include <linux/hugetlb.h>
#include <asm/acpi.h>
#include <asm/bug.h>
#include <asm/cmpxchg.h>
#include <asm/cpufeature.h>
@ -47,8 +49,6 @@
#include <asm/tlbflush.h>
#include <asm/traps.h>
#include <acpi/ghes.h>
struct fault_info {
int (*fn)(unsigned long addr, unsigned int esr,
struct pt_regs *regs);
@ -643,19 +643,10 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
inf = esr_to_fault_info(esr);
/*
* Synchronous aborts may interrupt code which had interrupts masked.
* Before calling out into the wider kernel tell the interested
* subsystems.
* Return value ignored as we rely on signal merging.
* Future patches will make this more robust.
*/
if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
if (interrupts_enabled(regs))
nmi_enter();
ghes_notify_sea();
if (interrupts_enabled(regs))
nmi_exit();
}
apei_claim_sea(regs);
if (esr & ESR_ELx_FnV)
siaddr = NULL;
@ -733,11 +724,6 @@ static const struct fault_info fault_info[] = {
{ do_bad, SIGKILL, SI_KERNEL, "unknown 63" },
};
int kvm_handle_guest_sea(phys_addr_t addr, unsigned int esr)
{
return ghes_notify_sea();
}
asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{