Commit 1d353dae authored by Carlos López's avatar Carlos López Committed by Sean Christopherson
Browse files

KVM: SVM: Move lock-protected allocation of SEV ASID into a separate helper 



Extract the lock-protected parts of SEV ASID allocation into a new helper
and opportunistically convert it to use guard() when acquiring the mutex.

Preserve the goto even though it's a little odd, as it's there's a fair
amount of subtlety that makes it surprisingly difficult to replicate the
functionality with a loop construct, and arguably using goto yields the
most readable code.

No functional change intended.

Signed-off-by: default avatarCarlos López <clopez@suse.de>
[sean: move code to separate helper, rework shortlog+changelog]
Link: https://patch.msgid.link/20260310234829.2608037-21-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent f09b7f4a

arch/x86/kvm/svm/sev.c

+23 −14
Original line number Diff line number Diff line
@@ -237,6 +237,28 @@ static void sev_misc_cg_uncharge(struct kvm_sev_info *sev) 
	misc_cg_uncharge(type, sev->misc_cg, 1);

}



static unsigned int sev_alloc_asid(unsigned int min_asid, unsigned int max_asid)

{

	unsigned int asid;

	bool retry = true;



	guard(mutex)(&sev_bitmap_lock);



again:

	asid = find_next_zero_bit(sev_asid_bitmap, max_asid + 1, min_asid);

	if (asid > max_asid) {

		if (retry && __sev_recycle_asids(min_asid, max_asid)) {

			retry = false;

			goto again;

		}



		return asid;

	}



	__set_bit(asid, sev_asid_bitmap);

	return asid;

}



static int sev_asid_new(struct kvm_sev_info *sev, unsigned long vm_type)

{

	/*
@@ -244,7 +266,6 @@ static int sev_asid_new(struct kvm_sev_info *sev, unsigned long vm_type) 
	 * SEV-ES-enabled guest can use from 1 to min_sev_asid - 1.

	 */

	unsigned int min_asid, max_asid, asid;

	bool retry = true;

	int ret;



	if (vm_type == KVM_X86_SNP_VM) {
@@ -277,24 +298,12 @@ static int sev_asid_new(struct kvm_sev_info *sev, unsigned long vm_type) 
		return ret;

	}



	mutex_lock(&sev_bitmap_lock);



again:

	asid = find_next_zero_bit(sev_asid_bitmap, max_asid + 1, min_asid);

	asid = sev_alloc_asid(min_asid, max_asid);

	if (asid > max_asid) {

		if (retry && __sev_recycle_asids(min_asid, max_asid)) {

			retry = false;

			goto again;

		}

		mutex_unlock(&sev_bitmap_lock);

		ret = -EBUSY;

		goto e_uncharge;

	}



	__set_bit(asid, sev_asid_bitmap);



	mutex_unlock(&sev_bitmap_lock);



	sev->asid = asid;

	return 0;

e_uncharge: