Commit 480e5926 authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Heiko Carstens
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[S390] kvm: fix address mode switching 



598841ca ([S390] use gmap address
spaces for kvm guest images) changed kvm to use a separate address
space for kvm guests. This address space was switched in __vcpu_run
In some cases (preemption, page fault) there is the possibility that
this address space switch is lost.
The typical symptom was a huge amount of validity intercepts or
random guest addressing exceptions.
Fix this by doing the switch in sie_loop and sie_exit and saving the
address space in the gmap structure itself. Also use the preempt
notifier.

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: default avatarAvi Kivity <avi@redhat.com>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
parent 9d037a77

arch/s390/include/asm/pgtable.h

+2 −0
Original line number Diff line number Diff line
@@ -658,12 +658,14 @@ static inline void pgste_set_pte(pte_t *ptep, pgste_t pgste) 
 * struct gmap_struct - guest address space

 * @mm: pointer to the parent mm_struct

 * @table: pointer to the page directory

 * @asce: address space control element for gmap page table

 * @crst_list: list of all crst tables used in the guest address space

 */

struct gmap {

	struct list_head list;

	struct mm_struct *mm;

	unsigned long *table;

	unsigned long asce;

	struct list_head crst_list;

};

arch/s390/kernel/asm-offsets.c

+3 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/sched.h>

#include <asm/vdso.h>

#include <asm/sigp.h>

#include <asm/pgtable.h>



/*

 * Make sure that the compiler is new enough. We want a compiler that
@@ -126,6 +127,7 @@ int main(void) 
	DEFINE(__LC_KERNEL_STACK, offsetof(struct _lowcore, kernel_stack));

	DEFINE(__LC_ASYNC_STACK, offsetof(struct _lowcore, async_stack));

	DEFINE(__LC_PANIC_STACK, offsetof(struct _lowcore, panic_stack));

	DEFINE(__LC_USER_ASCE, offsetof(struct _lowcore, user_asce));

	DEFINE(__LC_INT_CLOCK, offsetof(struct _lowcore, int_clock));

	DEFINE(__LC_MCCK_CLOCK, offsetof(struct _lowcore, mcck_clock));

	DEFINE(__LC_MACHINE_FLAGS, offsetof(struct _lowcore, machine_flags));
@@ -151,6 +153,7 @@ int main(void) 
	DEFINE(__LC_VDSO_PER_CPU, offsetof(struct _lowcore, vdso_per_cpu_data));

	DEFINE(__LC_GMAP, offsetof(struct _lowcore, gmap));

	DEFINE(__LC_CMF_HPP, offsetof(struct _lowcore, cmf_hpp));

	DEFINE(__GMAP_ASCE, offsetof(struct gmap, asce));

#endif /* CONFIG_32BIT */

	return 0;

}

arch/s390/kernel/entry64.S

+6 −0
Original line number Diff line number Diff line
@@ -1076,6 +1076,11 @@ sie_loop: 
	lg	%r14,__LC_THREAD_INFO		# pointer thread_info struct

	tm	__TI_flags+7(%r14),_TIF_EXIT_SIE

	jnz	sie_exit

	lg	%r14,__LC_GMAP			# get gmap pointer

	ltgr	%r14,%r14

	jz	sie_gmap

	lctlg	%c1,%c1,__GMAP_ASCE(%r14)	# load primary asce

sie_gmap:

	lg	%r14,__SF_EMPTY(%r15)		# get control block pointer

	SPP	__SF_EMPTY(%r15)		# set guest id

	sie	0(%r14)
@@ -1083,6 +1088,7 @@ sie_done: 
	SPP	__LC_CMF_HPP			# set host id

	lg	%r14,__LC_THREAD_INFO		# pointer thread_info struct

sie_exit:

	lctlg	%c1,%c1,__LC_USER_ASCE		# load primary asce

	ni	__TI_flags+6(%r14),255-(_TIF_SIE>>8)

	lg	%r14,__SF_EMPTY+8(%r15)		# load guest register save area

	stmg	%r0,%r13,0(%r14)		# save guest gprs 0-13

arch/s390/kvm/kvm-s390.c

+2 −2
Original line number Diff line number Diff line
@@ -263,10 +263,12 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) 
	vcpu->arch.guest_fpregs.fpc &= FPC_VALID_MASK;

	restore_fp_regs(&vcpu->arch.guest_fpregs);

	restore_access_regs(vcpu->arch.guest_acrs);

	gmap_enable(vcpu->arch.gmap);

}



void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)

{

	gmap_disable(vcpu->arch.gmap);

	save_fp_regs(&vcpu->arch.guest_fpregs);

	save_access_regs(vcpu->arch.guest_acrs);

	restore_fp_regs(&vcpu->arch.host_fpregs);
@@ -461,7 +463,6 @@ static void __vcpu_run(struct kvm_vcpu *vcpu) 
	local_irq_disable();

	kvm_guest_enter();

	local_irq_enable();

	gmap_enable(vcpu->arch.gmap);

	VCPU_EVENT(vcpu, 6, "entering sie flags %x",

		   atomic_read(&vcpu->arch.sie_block->cpuflags));

	if (sie64a(vcpu->arch.sie_block, vcpu->arch.guest_gprs)) {
@@ -470,7 +471,6 @@ static void __vcpu_run(struct kvm_vcpu *vcpu) 
	}

	VCPU_EVENT(vcpu, 6, "exit sie icptcode %d",

		   vcpu->arch.sie_block->icptcode);

	gmap_disable(vcpu->arch.gmap);

	local_irq_disable();

	kvm_guest_exit();

	local_irq_enable();

arch/s390/mm/pgtable.c

+2 −8
Original line number Diff line number Diff line
@@ -160,6 +160,8 @@ struct gmap *gmap_alloc(struct mm_struct *mm) 
	table = (unsigned long *) page_to_phys(page);

	crst_table_init(table, _REGION1_ENTRY_EMPTY);

	gmap->table = table;

	gmap->asce = _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH |

		     _ASCE_USER_BITS | __pa(table);

	list_add(&gmap->list, &mm->context.gmap_list);

	return gmap;
@@ -240,10 +242,6 @@ EXPORT_SYMBOL_GPL(gmap_free); 
 */

void gmap_enable(struct gmap *gmap)

{

	/* Load primary space page table origin. */

	S390_lowcore.user_asce = _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH |

				 _ASCE_USER_BITS | __pa(gmap->table);

	asm volatile("lctlg 1,1,%0\n" : : "m" (S390_lowcore.user_asce) );

	S390_lowcore.gmap = (unsigned long) gmap;

}

EXPORT_SYMBOL_GPL(gmap_enable);
@@ -254,10 +252,6 @@ EXPORT_SYMBOL_GPL(gmap_enable); 
 */

void gmap_disable(struct gmap *gmap)

{

	/* Load primary space page table origin. */

	S390_lowcore.user_asce =

		gmap->mm->context.asce_bits | __pa(gmap->mm->pgd);

	asm volatile("lctlg 1,1,%0\n" : : "m" (S390_lowcore.user_asce) );

	S390_lowcore.gmap = 0UL;

}

EXPORT_SYMBOL_GPL(gmap_disable);

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