Commit a413f474 authored by Ian Munsie's avatar Ian Munsie Committed by Benjamin Herrenschmidt
Browse files

powerpc: Disable relocation on exceptions whenever PR KVM is active 



For PR KVM we allow userspace to map 0xc000000000000000. Because
transitioning from userspace to the guest kernel may use the relocated
exception vectors we have to disable relocation on exceptions whenever
PR KVM is active as we cannot trust that address.

This issue does not apply to HV KVM, since changing from a guest to the
hypervisor will never use the relocated exception vectors.

Currently the hypervisor interface only allows us to toggle relocation
on exceptions on a partition wide scope, so we need to globally disable
relocation on exceptions when the first PR KVM instance is started and
only re-enable them when all PR KVM instances have been destroyed.

It's a bit heavy handed, but until the hypervisor gives us a lightweight
way to toggle relocation on exceptions on a single thread it's only real
option.

Signed-off-by: default avatarIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 96f013fe

arch/powerpc/include/asm/hvcall.h

+9 −0
Original line number Original line Diff line number Diff line
@@ -395,6 +395,15 @@ static inline unsigned long cmo_get_page_size(void) 
{

{

	return CMO_PageSize;

	return CMO_PageSize;

}

}



extern long pSeries_enable_reloc_on_exc(void);

extern long pSeries_disable_reloc_on_exc(void);



#else



#define pSeries_enable_reloc_on_exc()  do {} while (0)

#define pSeries_disable_reloc_on_exc() do {} while (0)



#endif /* CONFIG_PPC_PSERIES */

#endif /* CONFIG_PPC_PSERIES */





#endif /* __ASSEMBLY__ */

#endif /* __ASSEMBLY__ */

arch/powerpc/kvm/book3s_pr.c

+18 −0
Original line number Original line Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include <asm/kvm_book3s.h>

#include <asm/kvm_book3s.h>

#include <asm/mmu_context.h>

#include <asm/mmu_context.h>

#include <asm/switch_to.h>

#include <asm/switch_to.h>

#include <asm/firmware.h>

#include <linux/gfp.h>

#include <linux/gfp.h>

#include <linux/sched.h>

#include <linux/sched.h>

#include <linux/vmalloc.h>

#include <linux/vmalloc.h>
@@ -1284,12 +1285,21 @@ void kvmppc_core_flush_memslot(struct kvm *kvm, struct kvm_memory_slot *memslot) 
{

{

}

}





static unsigned int kvm_global_user_count = 0;

static DEFINE_SPINLOCK(kvm_global_user_count_lock);



int kvmppc_core_init_vm(struct kvm *kvm)

int kvmppc_core_init_vm(struct kvm *kvm)

{

{

#ifdef CONFIG_PPC64

#ifdef CONFIG_PPC64

	INIT_LIST_HEAD(&kvm->arch.spapr_tce_tables);

	INIT_LIST_HEAD(&kvm->arch.spapr_tce_tables);

#endif

#endif





	if (firmware_has_feature(FW_FEATURE_SET_MODE)) {

		spin_lock(&kvm_global_user_count_lock);

		if (++kvm_global_user_count == 1)

			pSeries_disable_reloc_on_exc();

		spin_unlock(&kvm_global_user_count_lock);

	}

	return 0;

	return 0;

}

}
@@ -1298,6 +1308,14 @@ void kvmppc_core_destroy_vm(struct kvm *kvm) 
#ifdef CONFIG_PPC64

#ifdef CONFIG_PPC64

	WARN_ON(!list_empty(&kvm->arch.spapr_tce_tables));

	WARN_ON(!list_empty(&kvm->arch.spapr_tce_tables));

#endif

#endif



	if (firmware_has_feature(FW_FEATURE_SET_MODE)) {

		spin_lock(&kvm_global_user_count_lock);

		BUG_ON(kvm_global_user_count == 0);

		if (--kvm_global_user_count == 0)

			pSeries_enable_reloc_on_exc();

		spin_unlock(&kvm_global_user_count_lock);

	}

}

}





static int kvmppc_book3s_init(void)

static int kvmppc_book3s_init(void)

arch/powerpc/platforms/pseries/setup.c

+5 −3
Original line number Original line Diff line number Diff line
@@ -375,7 +375,7 @@ static void pSeries_idle(void) 
 * to ever be a problem in practice we can move this into a kernel thread to

 * to ever be a problem in practice we can move this into a kernel thread to

 * finish off the process later in boot.

 * finish off the process later in boot.

 */

 */

static int __init pSeries_enable_reloc_on_exc(void)

long pSeries_enable_reloc_on_exc(void)

{

{

	long rc;

	long rc;

	unsigned int delay, total_delay = 0;

	unsigned int delay, total_delay = 0;
@@ -397,9 +397,9 @@ static int __init pSeries_enable_reloc_on_exc(void) 
		mdelay(delay);

		mdelay(delay);

	}

	}

}

}

EXPORT_SYMBOL(pSeries_enable_reloc_on_exc);





#ifdef CONFIG_KEXEC

long pSeries_disable_reloc_on_exc(void)

static long pSeries_disable_reloc_on_exc(void)

{

{

	long rc;

	long rc;
@@ -410,7 +410,9 @@ static long pSeries_disable_reloc_on_exc(void) 
		mdelay(get_longbusy_msecs(rc));

		mdelay(get_longbusy_msecs(rc));

	}

	}

}

}

EXPORT_SYMBOL(pSeries_disable_reloc_on_exc);





#ifdef CONFIG_KEXEC

static void pSeries_machine_kexec(struct kimage *image)

static void pSeries_machine_kexec(struct kimage *image)

{

{

	long rc;

	long rc;

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