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Message-Id: <20210816150718.3063877-3-scgl@linux.ibm.com>
Date: Mon, 16 Aug 2021 17:07:17 +0200
From: Janis Schoetterl-Glausch <scgl@...ux.ibm.com>
To: kvm@...r.kernel.org, borntraeger@...ibm.com, frankja@...ux.ibm.com,
imbrenda@...ux.ibm.com, Heiko Carstens <hca@...ux.ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>
Cc: scgl@...ux.ibm.com, david@...hat.com, cohuck@...hat.com,
linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] KVM: s390: gaccess: Refactor access address range check
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@...ux.ibm.com>
---
arch/s390/kvm/gaccess.c | 91 ++++++++++++++++++-----------------------
1 file changed, 39 insertions(+), 52 deletions(-)
diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index df83de0843de..e5a19d8b30e2 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -794,35 +794,45 @@ 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)
+/* Stores the gpas for each page in a real/virtual range into @gpas
+ * Modifies the 'struct kvm_s390_pgm_info pgm' member of @vcpu in the same
+ * way read_guest/write_guest do, the meaning of the return value is likewise
+ * the same.
+ * If @gpas is NULL only the checks are performed.
+ */
+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 long gpa;
+ unsigned int seg;
+ unsigned int offset = offset_in_page(ga);
int lap_enabled, rc = 0;
enum prot_type prot;
lap_enabled = low_address_protection_enabled(vcpu, asce);
- while (nr_pages) {
+ while ((seg = min(PAGE_SIZE - offset, len)) != 0) {
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 += seg;
+ len -= seg;
}
return 0;
}
@@ -845,10 +855,10 @@ 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 nr_pages, idx;
unsigned int seg;
- unsigned long pages_array[2];
- unsigned long *pages;
+ unsigned long gpa_array[2];
+ unsigned long *gpas;
int need_ipte_lock;
union asce asce;
int rc;
@@ -860,27 +870,25 @@ 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);
- seg = min(PAGE_SIZE - offset_in_page(gpa), len);
- rc = access_guest_frame(vcpu->kvm, mode, gpa, data, seg);
+ seg = min(PAGE_SIZE - offset_in_page(gpas[idx]), len);
+ rc = access_guest_frame(vcpu->kvm, mode, gpas[idx], data, seg);
len -= seg;
- ga += seg;
data += seg;
}
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;
}
@@ -914,8 +922,6 @@ 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;
@@ -923,23 +929,7 @@ 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);
}
/**
@@ -948,17 +938,14 @@ 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;
--
2.25.1
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