[PATCH v2 03/11] KVM: s390: handle_tprot: Honor storage keys

Janis Schoetterl-Glausch
2022-02-07T17:16:44Z

Use the access key operand to check for key protection when
translating guest addresses.
Since the translation code checks for accessing exceptions/error hvas,
we can remove the check here and simplify the control flow.
Keep checking if the memory is read-only even if such memslots are
currently not supported.

handle_tprot was the last user of guest_translate_address,
so remove it.

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>
---
arch/s390/kvm/gaccess.c | 9 ------
arch/s390/kvm/gaccess.h | 3 --
arch/s390/kvm/priv.c | 66 ++++++++++++++++++++++-------------------
3 files changed, 35 insertions(+), 43 deletions(-)

diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index 7fca0cff4c12..37838f637707 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -1118,15 +1118,6 @@ int guest_translate_address_with_key(struct kvm_vcpu *vcpu, unsigned long gva, u
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);
-}
-
/**
* check_gva_range - test a range of guest virtual addresses for accessibility
* @vcpu: virtual cpu
diff --git a/arch/s390/kvm/gaccess.h b/arch/s390/kvm/gaccess.h
index e5b2f56e7962..c5f2e7311b17 100644
--- a/arch/s390/kvm/gaccess.h
+++ b/arch/s390/kvm/gaccess.h
@@ -190,9 +190,6 @@ int guest_translate_address_with_key(struct kvm_vcpu *vcpu, unsigned long gva, u
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, u8 access_key);

diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 417154b314a6..30b24c42ef99 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -1443,10 +1443,11 @@ int kvm_s390_handle_eb(struct kvm_vcpu *vcpu)

static int handle_tprot(struct kvm_vcpu *vcpu)
{
- u64 address1, address2;
- unsigned long hva, gpa;
- int ret = 0, cc = 0;
+ u64 address, operand2;
+ unsigned long gpa;
+ u8 access_key;
bool writable;
+ int ret, cc;
u8 ar;

vcpu->stat.instruction_tprot++;
@@ -1454,43 +1455,46 @@ static int handle_tprot(struct kvm_vcpu *vcpu)
if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);

- kvm_s390_get_base_disp_sse(vcpu, &address1, &address2, &ar, NULL);
+ kvm_s390_get_base_disp_sse(vcpu, &address, &operand2, &ar, NULL);
+ access_key = (operand2 & 0xf0) >> 4;

- /* we only handle the Linux memory detection case:
- * access key == 0
- * everything else goes to userspace. */
- if (address2 & 0xf0)
- return -EOPNOTSUPP;
if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_DAT)
ipte_lock(vcpu);
- ret = guest_translate_address(vcpu, address1, ar, &gpa, GACC_STORE);
- if (ret == PGM_PROTECTION) {
+
+ ret = guest_translate_address_with_key(vcpu, address, ar, &gpa,
+ GACC_STORE, access_key);
+ if (ret == 0) {
+ gfn_to_hva_prot(vcpu->kvm, gpa_to_gfn(gpa), &writable);
+ } else if (ret == PGM_PROTECTION) {
+ writable = false;
/* Write protected? Try again with read-only... */
- cc = 1;
- ret = guest_translate_address(vcpu, address1, ar, &gpa,
- GACC_FETCH);
+ ret = guest_translate_address_with_key(vcpu, address, ar, &gpa,
+ GACC_FETCH, access_key);
}
- if (ret) {
- if (ret == PGM_ADDRESSING || ret == PGM_TRANSLATION_SPEC) {
- ret = kvm_s390_inject_program_int(vcpu, ret);
- } else if (ret > 0) {
- /* Translation not available */
- kvm_s390_set_psw_cc(vcpu, 3);
+ if (ret >= 0) {
+ cc = -1;
+
+ /* Fetching permitted; storing permitted */
+ if (ret == 0 && writable)
+ cc = 0;
+ /* Fetching permitted; storing not permitted */
+ else if (ret == 0 && !writable)
+ cc = 1;
+ /* Fetching not permitted; storing not permitted */
+ else if (ret == PGM_PROTECTION)
+ cc = 2;
+ /* Translation not available */
+ else if (ret != PGM_ADDRESSING && ret != PGM_TRANSLATION_SPEC)
+ cc = 3;
+
+ if (cc != -1) {
+ kvm_s390_set_psw_cc(vcpu, cc);
ret = 0;
+ } else {
+ ret = kvm_s390_inject_program_int(vcpu, ret);
}
- goto out_unlock;
}

- hva = gfn_to_hva_prot(vcpu->kvm, gpa_to_gfn(gpa), &writable);
- if (kvm_is_error_hva(hva)) {
- ret = kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
- } else {
- if (!writable)
- cc = 1; /* Write not permitted ==> read-only */
- kvm_s390_set_psw_cc(vcpu, cc);
- /* Note: CC2 only occurs for storage keys (not supported yet) */
- }
-out_unlock:
if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_DAT)
ipte_unlock(vcpu);
return ret;
--
2.32.0