diff options
Diffstat (limited to 'arch/s390/kvm/gaccess.c')
| -rw-r--r-- | arch/s390/kvm/gaccess.c | 250 |
1 files changed, 238 insertions, 12 deletions
diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c index 4460808c3b9a..d53a183c2005 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 +795,108 @@ static int low_address_protection_enabled(struct kvm_vcpu *vcpu, return 1; } +static int vm_check_access_key(struct kvm *kvm, u8 access_key, + enum gacc_mode mode, gpa_t gpa) +{ + u8 storage_key, access_control; + bool fetch_protected; + unsigned long hva; + int r; + + if (access_key == 0) + return 0; + + hva = gfn_to_hva(kvm, gpa_to_gfn(gpa)); + if (kvm_is_error_hva(hva)) + return PGM_ADDRESSING; + + 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); + if (access_control == access_key) + return 0; + fetch_protected = storage_key & _PAGE_FP_BIT; + if ((mode == GACC_FETCH || mode == GACC_IFETCH) && !fetch_protected) + return 0; + return PGM_PROTECTION; +} + +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 +907,7 @@ 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 +934,8 @@ 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 +962,10 @@ 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 +989,74 @@ 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_abs_with_key(struct kvm *kvm, gpa_t gpa, void *data, + unsigned long len, enum gacc_mode mode, u8 access_key) +{ + int offset = offset_in_page(gpa); + int fragment_len; + int rc; + + while (min(PAGE_SIZE - offset, len) > 0) { + fragment_len = min(PAGE_SIZE - offset, len); + rc = access_guest_page_with_key(kvm, mode, gpa, data, fragment_len, access_key); + if (rc) + return rc; + offset = 0; + len -= fragment_len; + data += fragment_len; + gpa += fragment_len; + } + 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; int rc; if (!len) @@ -904,16 +1071,47 @@ 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 +1138,13 @@ 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 +1152,9 @@ 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 +1163,8 @@ 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); } /** @@ -973,9 +1174,10 @@ 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; @@ -984,13 +1186,37 @@ 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; } /** + * check_gpa_range - test a range of guest physical addresses for accessibility + * @kvm: virtual machine instance + * @gpa: guest physical address + * @length: length of test range + * @mode: access mode to test, relevant for storage keys + * @access_key: access key to mach the storage keys with + */ +int check_gpa_range(struct kvm *kvm, unsigned long gpa, unsigned long length, + enum gacc_mode mode, u8 access_key) +{ + unsigned int fragment_len; + int rc = 0; + + while (length && !rc) { + fragment_len = min(PAGE_SIZE - offset_in_page(gpa), length); + rc = vm_check_access_key(kvm, access_key, mode, gpa); + length -= fragment_len; + gpa += fragment_len; + } + return rc; +} + +/** * kvm_s390_check_low_addr_prot_real - check for low-address protection * @vcpu: virtual cpu * @gra: Guest real address |