Commit d44f1b8d authored by James Morse's avatar James Morse Committed by Rafael J. Wysocki
Browse files

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



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: default avatarJames Morse <james.morse@arm.com>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Tested-by: default avatarTyler Baicar <tbaicar@codeaurora.org>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 0db5e022

arch/arm64/include/asm/acpi.h

+3 −1
Original line number Diff line number Diff line
@@ -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

arch/arm64/include/asm/daifflags.h

+1 −0
Original line number Diff line number Diff line
@@ -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)

arch/arm64/include/asm/kvm_ras.h

+15 −1
Original line number Diff line number Diff line
@@ -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__ */

arch/arm64/kernel/acpi.c

+31 −0
Original line number Diff line number Diff line
@@ -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;

}

arch/arm64/mm/fault.c

+5 −19
Original line number Diff line number Diff line
@@ -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)

{

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