Re: [PATCH v2 02/11] KVM: s390: Honor storage keys when accessing guest memory

Christian Borntraeger
2022-02-08T14:02:27Z

Am 07.02.22 um 17:59 schrieb Janis Schoetterl-Glausch:
> Storage key checking had not been implemented for instructions emulated
> by KVM. Implement it by enhancing the functions used for guest access,
> in particular those making use of access_guest which has been renamed
> to access_guest_with_key.
> Accesses via access_guest_real should not be key checked.
>
> For actual accesses, key checking is done by
> copy_from/to_user_key (which internally uses MVCOS/MVCP/MVCS).
> In cases where accessibility is checked without an actual access,
> this is performed by getting the storage key and checking if the access
> key matches. In both cases, if applicable, storage and fetch protection
> override are honored.
>
> Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
> Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>

> ---
> arch/s390/include/asm/ctl_reg.h | 2 +
> arch/s390/include/asm/page.h | 2 +
> arch/s390/kvm/gaccess.c | 187 ++++++++++++++++++++++++++++++--
> arch/s390/kvm/gaccess.h | 77 +++++++++++--
> arch/s390/kvm/intercept.c | 12 +-
> arch/s390/kvm/kvm-s390.c | 4 +-
> 6 files changed, 253 insertions(+), 31 deletions(-)
>
> diff --git a/arch/s390/include/asm/ctl_reg.h b/arch/s390/include/asm/ctl_reg.h
> index 04dc65f8901d..c800199a376b 100644
> --- a/arch/s390/include/asm/ctl_reg.h
> +++ b/arch/s390/include/asm/ctl_reg.h
> @@ -12,6 +12,8 @@
>
> #define CR0_CLOCK_COMPARATOR_SIGN BIT(63 - 10)
> #define CR0_LOW_ADDRESS_PROTECTION BIT(63 - 35)
> +#define CR0_FETCH_PROTECTION_OVERRIDE BIT(63 - 38)
> +#define CR0_STORAGE_PROTECTION_OVERRIDE BIT(63 - 39)
> #define CR0_EMERGENCY_SIGNAL_SUBMASK BIT(63 - 49)
> #define CR0_EXTERNAL_CALL_SUBMASK BIT(63 - 50)
> #define CR0_CLOCK_COMPARATOR_SUBMASK BIT(63 - 52)
> diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
> index d98d17a36c7b..cfc4d6fb2385 100644
> --- a/arch/s390/include/asm/page.h
> +++ b/arch/s390/include/asm/page.h
> @@ -20,6 +20,8 @@
> #define PAGE_SIZE _PAGE_SIZE
> #define PAGE_MASK _PAGE_MASK
> #define PAGE_DEFAULT_ACC 0
> +/* storage-protection override */
> +#define PAGE_SPO_ACC 9
> #define PAGE_DEFAULT_KEY (PAGE_DEFAULT_ACC << 4)
>
> #define HPAGE_SHIFT 20
> diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
> index 4460808c3b9a..7fca0cff4c12 100644
> --- a/arch/s390/kvm/gaccess.c
> +++ b/arch/s390/kvm/gaccess.c
> @@ -10,6 +10,7 @@
> #include <linux/mm_types.h>
> #include <linux/err.h>
> #include <linux/pgtable.h>
> +#include <linux/bitfield.h>
>
> #include <asm/gmap.h>
> #include "kvm-s390.h"
> @@ -794,6 +795,79 @@ static int low_address_protection_enabled(struct kvm_vcpu *vcpu,
> return 1;
> }
>
> +static bool fetch_prot_override_applicable(struct kvm_vcpu *vcpu, enum gacc_mode mode,
> + union asce asce)
> +{
> + psw_t *psw = &vcpu->arch.sie_block->gpsw;
> + unsigned long override;
> +
> + if (mode == GACC_FETCH || mode == GACC_IFETCH) {
> + /* check if fetch protection override enabled */
> + override = vcpu->arch.sie_block->gcr[0];
> + override &= CR0_FETCH_PROTECTION_OVERRIDE;
> + /* not applicable if subject to DAT && private space */
> + override = override && !(psw_bits(*psw).dat && asce.p);
> + return override;
> + }
> + return false;
> +}
> +
> +static bool fetch_prot_override_applies(unsigned long ga, unsigned int len)
> +{
> + return ga < 2048 && ga + len <= 2048;
> +}
> +
> +static bool storage_prot_override_applicable(struct kvm_vcpu *vcpu)
> +{
> + /* check if storage protection override enabled */
> + return vcpu->arch.sie_block->gcr[0] & CR0_STORAGE_PROTECTION_OVERRIDE;
> +}
> +
> +static bool storage_prot_override_applies(u8 access_control)
> +{
> + /* matches special storage protection override key (9) -> allow */
> + return access_control == PAGE_SPO_ACC;
> +}
> +
> +static int vcpu_check_access_key(struct kvm_vcpu *vcpu, u8 access_key,
> + enum gacc_mode mode, union asce asce, gpa_t gpa,
> + unsigned long ga, unsigned int len)
> +{
> + u8 storage_key, access_control;
> + unsigned long hva;
> + int r;
> +
> + /* access key 0 matches any storage key -> allow */
> + if (access_key == 0)
> + return 0;
> + /*
> + * caller needs to ensure that gfn is accessible, so we can
> + * assume that this cannot fail
> + */
> + hva = gfn_to_hva(vcpu->kvm, gpa_to_gfn(gpa));
> + mmap_read_lock(current->mm);
> + r = get_guest_storage_key(current->mm, hva, &storage_key);
> + mmap_read_unlock(current->mm);
> + if (r)
> + return r;
> + access_control = FIELD_GET(_PAGE_ACC_BITS, storage_key);
> + /* access key matches storage key -> allow */
> + if (access_control == access_key)
> + return 0;
> + if (mode == GACC_FETCH || mode == GACC_IFETCH) {
> + /* it is a fetch and fetch protection is off -> allow */
> + if (!(storage_key & _PAGE_FP_BIT))
> + return 0;
> + if (fetch_prot_override_applicable(vcpu, mode, asce) &&
> + fetch_prot_override_applies(ga, len))
> + return 0;
> + }
> + if (storage_prot_override_applicable(vcpu) &&
> + storage_prot_override_applies(access_control))
> + return 0;
> + return PGM_PROTECTION;
> +}
> +
> /**
> * guest_range_to_gpas() - Calculate guest physical addresses of page fragments
> * covering a logical range
> @@ -804,6 +878,7 @@ static int low_address_protection_enabled(struct kvm_vcpu *vcpu,
> * @len: length of range in bytes
> * @asce: address-space-control element to use for translation
> * @mode: access mode
> + * @access_key: access key to mach the range's storage keys against
> *
> * Translate a logical range to a series of guest absolute addresses,
> * such that the concatenation of page fragments starting at each gpa make up
> @@ -830,7 +905,8 @@ static int low_address_protection_enabled(struct kvm_vcpu *vcpu,
> */
> static int guest_range_to_gpas(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
> unsigned long *gpas, unsigned long len,
> - const union asce asce, enum gacc_mode mode)
> + const union asce asce, enum gacc_mode mode,
> + u8 access_key)
> {
> psw_t *psw = &vcpu->arch.sie_block->gpsw;
> unsigned int offset = offset_in_page(ga);
> @@ -857,6 +933,10 @@ static int guest_range_to_gpas(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
> }
> if (rc)
> return trans_exc(vcpu, rc, ga, ar, mode, prot);
> + rc = vcpu_check_access_key(vcpu, access_key, mode, asce, gpa, ga,
> + fragment_len);
> + if (rc)
> + return trans_exc(vcpu, rc, ga, ar, mode, PROT_TYPE_KEYC);
> if (gpas)
> *gpas++ = gpa;
> offset = 0;
> @@ -880,16 +960,54 @@ static int access_guest_page(struct kvm *kvm, enum gacc_mode mode, gpa_t gpa,
> return rc;
> }
>
> -int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data,
> - unsigned long len, enum gacc_mode mode)
> +static int
> +access_guest_page_with_key(struct kvm *kvm, enum gacc_mode mode, gpa_t gpa,
> + void *data, unsigned int len, u8 access_key)
> +{
> + struct kvm_memory_slot *slot;
> + bool writable;
> + gfn_t gfn;
> + hva_t hva;
> + int rc;
> +
> + gfn = gpa >> PAGE_SHIFT;
> + slot = gfn_to_memslot(kvm, gfn);
> + hva = gfn_to_hva_memslot_prot(slot, gfn, &writable);
> +
> + if (kvm_is_error_hva(hva))
> + return PGM_ADDRESSING;
> + /*
> + * Check if it's a ro memslot, even tho that can't occur (they're unsupported).
> + * Don't try to actually handle that case.
> + */
> + if (!writable && mode == GACC_STORE)
> + return -EOPNOTSUPP;
> + hva += offset_in_page(gpa);
> + if (mode == GACC_STORE)
> + rc = copy_to_user_key((void __user *)hva, data, len, access_key);
> + else
> + rc = copy_from_user_key(data, (void __user *)hva, len, access_key);
> + if (rc)
> + return PGM_PROTECTION;
> + if (mode == GACC_STORE)
> + mark_page_dirty_in_slot(kvm, slot, gfn);
> + return 0;
> +}
> +
> +int access_guest_with_key(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
> + void *data, unsigned long len, enum gacc_mode mode,
> + u8 access_key)
> {
> psw_t *psw = &vcpu->arch.sie_block->gpsw;
> unsigned long nr_pages, idx;
> unsigned long gpa_array[2];
> unsigned int fragment_len;
> unsigned long *gpas;
> + enum prot_type prot;
> int need_ipte_lock;
> union asce asce;
> + bool try_storage_prot_override;
> + bool try_fetch_prot_override;

These are used only once, so we could get rid of those. On the other hands this
variant might be slightly more readable, so I am fine either way.

> int rc;
>
> if (!len)
> @@ -904,16 +1022,47 @@ int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data,
> gpas = vmalloc(array_size(nr_pages, sizeof(unsigned long)));
> if (!gpas)
> return -ENOMEM;
> + try_fetch_prot_override = fetch_prot_override_applicable(vcpu, mode, asce);
> + try_storage_prot_override = storage_prot_override_applicable(vcpu);
> need_ipte_lock = psw_bits(*psw).dat && !asce.r;
> if (need_ipte_lock)
> ipte_lock(vcpu);
> - rc = guest_range_to_gpas(vcpu, ga, ar, gpas, len, asce, mode);
> - for (idx = 0; idx < nr_pages && !rc; idx++) {
> + /*
> + * Since we do the access further down ultimately via a move instruction
> + * that does key checking and returns an error in case of a protection
> + * violation, we don't need to do the check during address translation.
> + * Skip it by passing access key 0, which matches any storage key,
> + * obviating the need for any further checks. As a result the check is
> + * handled entirely in hardware on access, we only need to take care to
> + * forego key protection checking if fetch protection override applies or
> + * retry with the special key 9 in case of storage protection override.
> + */
> + rc = guest_range_to_gpas(vcpu, ga, ar, gpas, len, asce, mode, 0);
> + if (rc)
> + goto out_unlock;
> + for (idx = 0; idx < nr_pages; idx++) {
> fragment_len = min(PAGE_SIZE - offset_in_page(gpas[idx]), len);
> - rc = access_guest_page(vcpu->kvm, mode, gpas[idx], data, fragment_len);
> + if (try_fetch_prot_override && fetch_prot_override_applies(ga, fragment_len)) {
> + rc = access_guest_page(vcpu->kvm, mode, gpas[idx],
> + data, fragment_len);
> + } else {
> + rc = access_guest_page_with_key(vcpu->kvm, mode, gpas[idx],
> + data, fragment_len, access_key);
> + }
> + if (rc == PGM_PROTECTION && try_storage_prot_override)
> + rc = access_guest_page_with_key(vcpu->kvm, mode, gpas[idx],
> + data, fragment_len, PAGE_SPO_ACC);
> + if (rc == PGM_PROTECTION)
> + prot = PROT_TYPE_KEYC;
> + if (rc)
> + break;
> len -= fragment_len;
> data += fragment_len;
> + ga = kvm_s390_logical_to_effective(vcpu, ga + fragment_len);
> }
> + if (rc > 0)
> + rc = trans_exc(vcpu, rc, ga, ar, mode, prot);
> +out_unlock:
> if (need_ipte_lock)
> ipte_unlock(vcpu);
> if (nr_pages > ARRAY_SIZE(gpa_array))
> @@ -940,12 +1089,13 @@ int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra,
> }
>
> /**
> - * guest_translate_address - translate guest logical into guest absolute address
> + * guest_translate_address_with_key - translate guest logical into guest absolute address
> * @vcpu: virtual cpu
> * @gva: Guest virtual address
> * @ar: Access register
> * @gpa: Guest physical address
> * @mode: Translation access mode
> + * @access_key: access key to mach the storage key with
> *
> * Parameter semantics are the same as the ones from guest_translate.
> * The memory contents at the guest address are not changed.
> @@ -953,8 +1103,9 @@ int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra,
> * Note: The IPTE lock is not taken during this function, so the caller
> * has to take care of this.
> */
> -int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
> - unsigned long *gpa, enum gacc_mode mode)
> +int guest_translate_address_with_key(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
> + unsigned long *gpa, enum gacc_mode mode,
> + u8 access_key)
> {
> union asce asce;
> int rc;
> @@ -963,7 +1114,17 @@ int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
> rc = get_vcpu_asce(vcpu, &asce, gva, ar, mode);
> if (rc)
> return rc;
> - return guest_range_to_gpas(vcpu, gva, ar, gpa, 1, asce, mode);
> + return guest_range_to_gpas(vcpu, gva, ar, gpa, 1, asce, mode,
> + access_key);
> +}
> +
> +int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
> + unsigned long *gpa, enum gacc_mode mode)
> +{
> + u8 access_key = psw_bits(vcpu->arch.sie_block->gpsw).key;
> +
> + return guest_translate_address_with_key(vcpu, gva, ar, gpa, mode,
> + access_key);
> }
>
> /**
> @@ -973,9 +1134,10 @@ int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
> * @ar: Access register
> * @length: Length of test range
> * @mode: Translation access mode
> + * @access_key: access key to mach the storage keys with
> */
> int check_gva_range(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
> - unsigned long length, enum gacc_mode mode)
> + unsigned long length, enum gacc_mode mode, u8 access_key)
> {
> union asce asce;
> int rc = 0;
> @@ -984,7 +1146,8 @@ int check_gva_range(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
> if (rc)
> return rc;
> ipte_lock(vcpu);
> - rc = guest_range_to_gpas(vcpu, gva, ar, NULL, length, asce, mode);
> + rc = guest_range_to_gpas(vcpu, gva, ar, NULL, length, asce, mode,
> + access_key);
> ipte_unlock(vcpu);
>
> return rc;
> diff --git a/arch/s390/kvm/gaccess.h b/arch/s390/kvm/gaccess.h
> index 7c72a5e3449f..e5b2f56e7962 100644
> --- a/arch/s390/kvm/gaccess.h
> +++ b/arch/s390/kvm/gaccess.h
> @@ -186,24 +186,31 @@ enum gacc_mode {
> GACC_IFETCH,
> };
>
> +int guest_translate_address_with_key(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
> + unsigned long *gpa, enum gacc_mode mode,
> + u8 access_key);
> +
> int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva,
> u8 ar, unsigned long *gpa, enum gacc_mode mode);
> +
> int check_gva_range(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar,
> - unsigned long length, enum gacc_mode mode);
> + unsigned long length, enum gacc_mode mode, u8 access_key);
>
> -int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data,
> - unsigned long len, enum gacc_mode mode);
> +int access_guest_with_key(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
> + void *data, unsigned long len, enum gacc_mode mode,
> + u8 access_key);
>
> int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra,
> void *data, unsigned long len, enum gacc_mode mode);
>
> /**
> - * write_guest - copy data from kernel space to guest space
> + * write_guest_with_key - copy data from kernel space to guest space
> * @vcpu: virtual cpu
> * @ga: guest address
> * @ar: access register
> * @data: source address in kernel space
> * @len: number of bytes to copy
> + * @access_key: access key the storage key needs to match
> *
> * Copy @len bytes from @data (kernel space) to @ga (guest address).
> * In order to copy data to guest space the PSW of the vcpu is inspected:
> @@ -214,8 +221,8 @@ int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra,
> * The addressing mode of the PSW is also inspected, so that address wrap
> * around is taken into account for 24-, 31- and 64-bit addressing mode,
> * if the to be copied data crosses page boundaries in guest address space.
> - * In addition also low address and DAT protection are inspected before
> - * copying any data (key protection is currently not implemented).
> + * In addition low address, DAT and key protection checks are performed before
> + * copying any data.
> *
> * This function modifies the 'struct kvm_s390_pgm_info pgm' member of @vcpu.
> * In case of an access exception (e.g. protection exception) pgm will contain
> @@ -243,10 +250,53 @@ int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra,
> * if data has been changed in guest space in case of an exception.
> */
> static inline __must_check
> +int write_guest_with_key(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
> + void *data, unsigned long len, u8 access_key)
> +{
> + return access_guest_with_key(vcpu, ga, ar, data, len, GACC_STORE,
> + access_key);
> +}
> +
> +/**
> + * write_guest - copy data from kernel space to guest space
> + * @vcpu: virtual cpu
> + * @ga: guest address
> + * @ar: access register
> + * @data: source address in kernel space
> + * @len: number of bytes to copy
> + *
> + * The behaviour of write_guest is identical to write_guest_with_key, except
> + * that the PSW access key is used instead of an explicit argument.
> + */
> +static inline __must_check
> int write_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data,
> unsigned long len)
> {
> - return access_guest(vcpu, ga, ar, data, len, GACC_STORE);
> + u8 access_key = psw_bits(vcpu->arch.sie_block->gpsw).key;
> +
> + return write_guest_with_key(vcpu, ga, ar, data, len, access_key);
> +}
> +
> +/**
> + * read_guest_with_key - copy data from guest space to kernel space
> + * @vcpu: virtual cpu
> + * @ga: guest address
> + * @ar: access register
> + * @data: destination address in kernel space
> + * @len: number of bytes to copy
> + * @access_key: access key the storage key needs to match
> + *
> + * Copy @len bytes from @ga (guest address) to @data (kernel space).
> + *
> + * The behaviour of read_guest_with_key is identical to write_guest_with_key,
> + * except that data will be copied from guest space to kernel space.
> + */
> +static inline __must_check
> +int read_guest_with_key(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
> + void *data, unsigned long len, u8 access_key)
> +{
> + return access_guest_with_key(vcpu, ga, ar, data, len, GACC_FETCH,
> + access_key);
> }
>
> /**
> @@ -259,14 +309,16 @@ int write_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data,
> *
> * Copy @len bytes from @ga (guest address) to @data (kernel space).
> *
> - * The behaviour of read_guest is identical to write_guest, except that
> - * data will be copied from guest space to kernel space.
> + * The behaviour of read_guest is identical to read_guest_with_key, except
> + * that the PSW access key is used instead of an explicit argument.
> */
> static inline __must_check
> int read_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data,
> unsigned long len)
> {
> - return access_guest(vcpu, ga, ar, data, len, GACC_FETCH);
> + u8 access_key = psw_bits(vcpu->arch.sie_block->gpsw).key;
> +
> + return read_guest_with_key(vcpu, ga, ar, data, len, access_key);
> }
>
> /**
> @@ -287,7 +339,10 @@ static inline __must_check
> int read_guest_instr(struct kvm_vcpu *vcpu, unsigned long ga, void *data,
> unsigned long len)
> {
> - return access_guest(vcpu, ga, 0, data, len, GACC_IFETCH);
> + u8 access_key = psw_bits(vcpu->arch.sie_block->gpsw).key;
> +
> + return access_guest_with_key(vcpu, ga, 0, data, len, GACC_IFETCH,
> + access_key);
> }
>
> /**
> diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
> index d07ff646d844..8bd42a20d924 100644
> --- a/arch/s390/kvm/intercept.c
> +++ b/arch/s390/kvm/intercept.c
> @@ -331,18 +331,18 @@ static int handle_mvpg_pei(struct kvm_vcpu *vcpu)
>
> kvm_s390_get_regs_rre(vcpu, &reg1, &reg2);
>
> - /* Make sure that the source is paged-in */
> - rc = guest_translate_address(vcpu, vcpu->run->s.regs.gprs[reg2],
> - reg2, &srcaddr, GACC_FETCH);
> + /* Ensure that the source is paged-in, no actual access -> no key checking */
> + rc = guest_translate_address_with_key(vcpu, vcpu->run->s.regs.gprs[reg2],
> + reg2, &srcaddr, GACC_FETCH, 0);
> if (rc)
> return kvm_s390_inject_prog_cond(vcpu, rc);
> rc = kvm_arch_fault_in_page(vcpu, srcaddr, 0);
> if (rc != 0)
> return rc;
>
> - /* Make sure that the destination is paged-in */
> - rc = guest_translate_address(vcpu, vcpu->run->s.regs.gprs[reg1],
> - reg1, &dstaddr, GACC_STORE);
> + /* Ensure that the source is paged-in, no actual access -> no key checking */
> + rc = guest_translate_address_with_key(vcpu, vcpu->run->s.regs.gprs[reg1],
> + reg1, &dstaddr, GACC_STORE, 0);
> if (rc)
> return kvm_s390_inject_prog_cond(vcpu, rc);
> rc = kvm_arch_fault_in_page(vcpu, dstaddr, 1);
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 577f1ead6a51..cf347e1a4f17 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -4711,7 +4711,7 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
> case KVM_S390_MEMOP_LOGICAL_READ:
> if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) {
> r = check_gva_range(vcpu, mop->gaddr, mop->ar,
> - mop->size, GACC_FETCH);
> + mop->size, GACC_FETCH, 0);
> break;
> }
> r = read_guest(vcpu, mop->gaddr, mop->ar, tmpbuf, mop->size);
> @@ -4723,7 +4723,7 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu,
> case KVM_S390_MEMOP_LOGICAL_WRITE:
> if (mop->flags & KVM_S390_MEMOP_F_CHECK_ONLY) {
> r = check_gva_range(vcpu, mop->gaddr, mop->ar,
> - mop->size, GACC_STORE);
> + mop->size, GACC_STORE, 0);
> break;
> }
> if (copy_from_user(tmpbuf, uaddr, mop->size)) {