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KVM: SVM: Do not set sev->es_active until KVM_SEV_ES_INIT completes

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Set sev->es_active only after the guts of KVM_SEV_ES_INIT succeeds.  If
the command fails, e.g. because SEV is already active or there are no
available ASIDs, then es_active will be left set even though the VM is
not fully SEV-ES capable.

Refactor the code so that "es_active" is passed on the stack instead of
being prematurely shoved into sev_info, both to avoid having to unwind
sev_info and so that it's more obvious what actually consumes es_active
in sev_guest_init() and its helpers.

Fixes: ad73109ae7 ("KVM: SVM: Provide support to launch and run an SEV-ES guest")
Cc: stable@vger.kernel.org
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210331031936.2495277-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-03-30 20:19:35 -07:00 committed by Paolo Bonzini
parent c36b16d29f
commit 9fa1521daa
1 changed files with 12 additions and 17 deletions
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29
arch/x86/kvm/svm/sev.c
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@ -87,7 +87,7 @@ static bool __sev_recycle_asids(int min_asid, int max_asid)
return true; return true;
} }
static int sev_asid_new(struct kvm_sev_info *sev) static int sev_asid_new(bool es_active)
{ {
int pos, min_asid, max_asid; int pos, min_asid, max_asid;
bool retry = true; bool retry = true;
@ -98,8 +98,8 @@ static int sev_asid_new(struct kvm_sev_info *sev)
* SEV-enabled guests must use asid from min_sev_asid to max_sev_asid. * SEV-enabled guests must use asid from min_sev_asid to max_sev_asid.
* SEV-ES-enabled guest can use from 1 to min_sev_asid - 1. * SEV-ES-enabled guest can use from 1 to min_sev_asid - 1.
*/ */
min_asid = sev->es_active ? 0 : min_sev_asid - 1; min_asid = es_active ? 0 : min_sev_asid - 1;
max_asid = sev->es_active ? min_sev_asid - 1 : max_sev_asid; max_asid = es_active ? min_sev_asid - 1 : max_sev_asid;
again: again:
pos = find_next_zero_bit(sev_asid_bitmap, max_sev_asid, min_asid); pos = find_next_zero_bit(sev_asid_bitmap, max_sev_asid, min_asid);
if (pos >= max_asid) { if (pos >= max_asid) {
@ -179,13 +179,14 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
{ {
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
bool es_active = argp->id == KVM_SEV_ES_INIT;
int asid, ret; int asid, ret;
ret = -EBUSY; ret = -EBUSY;
if (unlikely(sev->active)) if (unlikely(sev->active))
return ret; return ret;
asid = sev_asid_new(sev); asid = sev_asid_new(es_active);
if (asid < 0) if (asid < 0)
return ret; return ret;
@ -194,6 +195,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
goto e_free; goto e_free;
sev->active = true; sev->active = true;
sev->es_active = es_active;
sev->asid = asid; sev->asid = asid;
INIT_LIST_HEAD(&sev->regions_list); INIT_LIST_HEAD(&sev->regions_list);
@ -204,16 +206,6 @@ e_free:
return ret; return ret;
} }
static int sev_es_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
{
if (!sev_es)
return -ENOTTY;
to_kvm_svm(kvm)->sev_info.es_active = true;
return sev_guest_init(kvm, argp);
}
static int sev_bind_asid(struct kvm *kvm, unsigned int handle, int *error) static int sev_bind_asid(struct kvm *kvm, unsigned int handle, int *error)
{ {
struct sev_data_activate *data; struct sev_data_activate *data;
@ -1128,12 +1120,15 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
mutex_lock(&kvm->lock); mutex_lock(&kvm->lock);
switch (sev_cmd.id) { switch (sev_cmd.id) {
case KVM_SEV_ES_INIT:
if (!sev_es) {
r = -ENOTTY;
goto out;
}
fallthrough;
case KVM_SEV_INIT: case KVM_SEV_INIT:
r = sev_guest_init(kvm, &sev_cmd); r = sev_guest_init(kvm, &sev_cmd);
break; break;
case KVM_SEV_ES_INIT:
r = sev_es_guest_init(kvm, &sev_cmd);
break;
case KVM_SEV_LAUNCH_START: case KVM_SEV_LAUNCH_START:
r = sev_launch_start(kvm, &sev_cmd); r = sev_launch_start(kvm, &sev_cmd);
break; break;