4.19-stable review patch. If anyone has any objections, please let me know.
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From: Janis Schoetterl-Glausch scgl@linux.ibm.com
[ Upstream commit 7faa543df19bf62d4583a64d3902705747f2ad29 ]
Do not round down the first address to the page boundary, just translate it normally, which gives the value we care about in the first place. Given this, translating a single address is just the special case of translating a range spanning a single page.
Make the output optional, so the function can be used to just check a range.
Signed-off-by: Janis Schoetterl-Glausch scgl@linux.ibm.com Reviewed-by: Janosch Frank frankja@linux.ibm.com Reviewed-by: Claudio Imbrenda imbrenda@linux.ibm.com Message-Id: 20211126164549.7046-3-scgl@linux.ibm.com Signed-off-by: Janosch Frank frankja@linux.ibm.com Stable-dep-of: e8061f06185b ("KVM: s390: gaccess: Check if guest address is in memslot") Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/kvm/gaccess.c | 122 +++++++++++++++++++++++----------------- 1 file changed, 69 insertions(+), 53 deletions(-)
diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c index b184749ffc5ae..d4fe5db5984dd 100644 --- a/arch/s390/kvm/gaccess.c +++ b/arch/s390/kvm/gaccess.c @@ -794,35 +794,74 @@ static int low_address_protection_enabled(struct kvm_vcpu *vcpu, return 1; }
-static int guest_page_range(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, - unsigned long *pages, unsigned long nr_pages, - const union asce asce, enum gacc_mode mode) +/** + * guest_range_to_gpas() - Calculate guest physical addresses of page fragments + * covering a logical range + * @vcpu: virtual cpu + * @ga: guest address, start of range + * @ar: access register + * @gpas: output argument, may be NULL + * @len: length of range in bytes + * @asce: address-space-control element to use for translation + * @mode: access mode + * + * Translate a logical range to a series of guest absolute addresses, + * such that the concatenation of page fragments starting at each gpa make up + * the whole range. + * The translation is performed as if done by the cpu for the given @asce, @ar, + * @mode and state of the @vcpu. + * If the translation causes an exception, its program interruption code is + * returned and the &struct kvm_s390_pgm_info pgm member of @vcpu is modified + * such that a subsequent call to kvm_s390_inject_prog_vcpu() will inject + * a correct exception into the guest. + * The resulting gpas are stored into @gpas, unless it is NULL. + * + * Note: All fragments except the first one start at the beginning of a page. + * When deriving the boundaries of a fragment from a gpa, all but the last + * fragment end at the end of the page. + * + * Return: + * * 0 - success + * * <0 - translation could not be performed, for example if guest + * memory could not be accessed + * * >0 - an access exception occurred. In this case the returned value + * is the program interruption code and the contents of pgm may + * be used to inject an exception into the guest. + */ +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) { psw_t *psw = &vcpu->arch.sie_block->gpsw; + unsigned int offset = offset_in_page(ga); + unsigned int fragment_len; int lap_enabled, rc = 0; enum prot_type prot; + unsigned long gpa;
lap_enabled = low_address_protection_enabled(vcpu, asce); - while (nr_pages) { + while (min(PAGE_SIZE - offset, len) > 0) { + fragment_len = min(PAGE_SIZE - offset, len); ga = kvm_s390_logical_to_effective(vcpu, ga); if (mode == GACC_STORE && lap_enabled && is_low_address(ga)) return trans_exc(vcpu, PGM_PROTECTION, ga, ar, mode, PROT_TYPE_LA); - ga &= PAGE_MASK; if (psw_bits(*psw).dat) { - rc = guest_translate(vcpu, ga, pages, asce, mode, &prot); + rc = guest_translate(vcpu, ga, &gpa, asce, mode, &prot); if (rc < 0) return rc; } else { - *pages = kvm_s390_real_to_abs(vcpu, ga); - if (kvm_is_error_gpa(vcpu->kvm, *pages)) + gpa = kvm_s390_real_to_abs(vcpu, ga); + if (kvm_is_error_gpa(vcpu->kvm, gpa)) rc = PGM_ADDRESSING; } if (rc) return trans_exc(vcpu, rc, ga, ar, mode, prot); - ga += PAGE_SIZE; - pages++; - nr_pages--; + if (gpas) + *gpas++ = gpa; + offset = 0; + ga += fragment_len; + len -= fragment_len; } return 0; } @@ -831,10 +870,10 @@ int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data, unsigned long len, enum gacc_mode mode) { psw_t *psw = &vcpu->arch.sie_block->gpsw; - unsigned long nr_pages, gpa, idx; - unsigned long pages_array[2]; + unsigned long nr_pages, idx; + unsigned long gpa_array[2]; unsigned int fragment_len; - unsigned long *pages; + unsigned long *gpas; int need_ipte_lock; union asce asce; int rc; @@ -846,30 +885,28 @@ int access_guest(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar, void *data, if (rc) return rc; nr_pages = (((ga & ~PAGE_MASK) + len - 1) >> PAGE_SHIFT) + 1; - pages = pages_array; - if (nr_pages > ARRAY_SIZE(pages_array)) - pages = vmalloc(array_size(nr_pages, sizeof(unsigned long))); - if (!pages) + gpas = gpa_array; + if (nr_pages > ARRAY_SIZE(gpa_array)) + gpas = vmalloc(array_size(nr_pages, sizeof(unsigned long))); + if (!gpas) return -ENOMEM; need_ipte_lock = psw_bits(*psw).dat && !asce.r; if (need_ipte_lock) ipte_lock(vcpu); - rc = guest_page_range(vcpu, ga, ar, pages, nr_pages, asce, mode); + rc = guest_range_to_gpas(vcpu, ga, ar, gpas, len, asce, mode); for (idx = 0; idx < nr_pages && !rc; idx++) { - gpa = pages[idx] + offset_in_page(ga); - fragment_len = min(PAGE_SIZE - offset_in_page(gpa), len); + fragment_len = min(PAGE_SIZE - offset_in_page(gpas[idx]), len); if (mode == GACC_STORE) - rc = kvm_write_guest(vcpu->kvm, gpa, data, fragment_len); + rc = kvm_write_guest(vcpu->kvm, gpas[idx], data, fragment_len); else - rc = kvm_read_guest(vcpu->kvm, gpa, data, fragment_len); + rc = kvm_read_guest(vcpu->kvm, gpas[idx], data, fragment_len); len -= fragment_len; - ga += fragment_len; data += fragment_len; } if (need_ipte_lock) ipte_unlock(vcpu); - if (nr_pages > ARRAY_SIZE(pages_array)) - vfree(pages); + if (nr_pages > ARRAY_SIZE(gpa_array)) + vfree(gpas); return rc; }
@@ -906,8 +943,6 @@ int access_guest_real(struct kvm_vcpu *vcpu, unsigned long gra, int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar, unsigned long *gpa, enum gacc_mode mode) { - psw_t *psw = &vcpu->arch.sie_block->gpsw; - enum prot_type prot; union asce asce; int rc;
@@ -915,23 +950,7 @@ 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; - if (is_low_address(gva) && low_address_protection_enabled(vcpu, asce)) { - if (mode == GACC_STORE) - return trans_exc(vcpu, PGM_PROTECTION, gva, 0, - mode, PROT_TYPE_LA); - } - - if (psw_bits(*psw).dat && !asce.r) { /* Use DAT? */ - rc = guest_translate(vcpu, gva, gpa, asce, mode, &prot); - if (rc > 0) - return trans_exc(vcpu, rc, gva, 0, mode, prot); - } else { - *gpa = kvm_s390_real_to_abs(vcpu, gva); - if (kvm_is_error_gpa(vcpu->kvm, *gpa)) - return trans_exc(vcpu, rc, gva, PGM_ADDRESSING, mode, 0); - } - - return rc; + return guest_range_to_gpas(vcpu, gva, ar, gpa, 1, asce, mode); }
/** @@ -940,17 +959,14 @@ int guest_translate_address(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar, int check_gva_range(struct kvm_vcpu *vcpu, unsigned long gva, u8 ar, unsigned long length, enum gacc_mode mode) { - unsigned long gpa; - unsigned long currlen; + union asce asce; int rc = 0;
+ rc = get_vcpu_asce(vcpu, &asce, gva, ar, mode); + if (rc) + return rc; ipte_lock(vcpu); - while (length > 0 && !rc) { - currlen = min(length, PAGE_SIZE - (gva % PAGE_SIZE)); - rc = guest_translate_address(vcpu, gva, ar, &gpa, mode); - gva += currlen; - length -= currlen; - } + rc = guest_range_to_gpas(vcpu, gva, ar, NULL, length, asce, mode); ipte_unlock(vcpu);
return rc;