linux-kernel - [RFC PATCH v2 07/13] KVM: x86: Refactor sev's flag migration_in

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Message-ID: <6ef77cc986aa89c1799cf3709de30edd6e4e70ee.1747368093.git.afranji@google.com>
Date: Fri, 16 May 2025 19:19:27 +0000
From: Ryan Afranji <afranji@...gle.com>
To: afranji@...gle.com, ackerleytng@...gle.com, pbonzini@...hat.com, 
	seanjc@...gle.com, tglx@...utronix.de, x86@...nel.org, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	tabba@...gle.com
Cc: mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com, hpa@...or.com, 
	shuah@...nel.org, andrew.jones@...ux.dev, ricarkol@...gle.com, 
	chao.p.peng@...ux.intel.com, jarkko@...nel.org, yu.c.zhang@...ux.intel.com, 
	vannapurve@...gle.com, erdemaktas@...gle.com, mail@...iej.szmigiero.name, 
	vbabka@...e.cz, david@...hat.com, qperret@...gle.com, michael.roth@....com, 
	wei.w.wang@...el.com, liam.merwick@...cle.com, isaku.yamahata@...il.com, 
	kirill.shutemov@...ux.intel.com, sagis@...gle.com, jthoughton@...gle.com
Subject: [RFC PATCH v2 07/13] KVM: x86: Refactor sev's flag
 migration_in_progress to kvm struct

From: Ackerley Tng <ackerleytng@...gle.com>

The migration_in_progress flag will also be needed for migration of
non-sev VMs.

Co-developed-by: Sagi Shahar <sagis@...gle.com>
Signed-off-by: Sagi Shahar <sagis@...gle.com>
Co-developed-by: Vishal Annapurve <vannapurve@...gle.com>
Signed-off-by: Vishal Annapurve <vannapurve@...gle.com>
Signed-off-by: Ackerley Tng <ackerleytng@...gle.com>
Signed-off-by: Ryan Afranji <afranji@...gle.com>
---
 arch/x86/kvm/svm/sev.c   | 17 ++++++-----------
 arch/x86/kvm/svm/svm.h   |  1 -
 include/linux/kvm_host.h |  1 +
 3 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 0bc708ee2788..89c06cfcc200 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1838,8 +1838,6 @@ static bool is_cmd_allowed_from_mirror(u32 cmd_id)
 
 static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)
 {
-	struct kvm_sev_info *dst_sev = to_kvm_sev_info(dst_kvm);
-	struct kvm_sev_info *src_sev = to_kvm_sev_info(src_kvm);
 	int r = -EBUSY;
 
 	if (dst_kvm == src_kvm)
@@ -1849,10 +1847,10 @@ static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)
 	 * Bail if these VMs are already involved in a migration to avoid
 	 * deadlock between two VMs trying to migrate to/from each other.
 	 */
-	if (atomic_cmpxchg_acquire(&dst_sev->migration_in_progress, 0, 1))
+	if (atomic_cmpxchg_acquire(&dst_kvm->migration_in_progress, 0, 1))
 		return -EBUSY;
 
-	if (atomic_cmpxchg_acquire(&src_sev->migration_in_progress, 0, 1))
+	if (atomic_cmpxchg_acquire(&src_kvm->migration_in_progress, 0, 1))
 		goto release_dst;
 
 	r = -EINTR;
@@ -1865,21 +1863,18 @@ static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)
 unlock_dst:
 	mutex_unlock(&dst_kvm->lock);
 release_src:
-	atomic_set_release(&src_sev->migration_in_progress, 0);
+	atomic_set_release(&src_kvm->migration_in_progress, 0);
 release_dst:
-	atomic_set_release(&dst_sev->migration_in_progress, 0);
+	atomic_set_release(&dst_kvm->migration_in_progress, 0);
 	return r;
 }
 
 static void sev_unlock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)
 {
-	struct kvm_sev_info *dst_sev = to_kvm_sev_info(dst_kvm);
-	struct kvm_sev_info *src_sev = to_kvm_sev_info(src_kvm);
-
 	mutex_unlock(&dst_kvm->lock);
 	mutex_unlock(&src_kvm->lock);
-	atomic_set_release(&dst_sev->migration_in_progress, 0);
-	atomic_set_release(&src_sev->migration_in_progress, 0);
+	atomic_set_release(&dst_kvm->migration_in_progress, 0);
+	atomic_set_release(&src_kvm->migration_in_progress, 0);
 }
 
 /* vCPU mutex subclasses.  */
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index d4490eaed55d..35df8be621c5 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -107,7 +107,6 @@ struct kvm_sev_info {
 	struct list_head mirror_vms; /* List of VMs mirroring */
 	struct list_head mirror_entry; /* Use as a list entry of mirrors */
 	struct misc_cg *misc_cg; /* For misc cgroup accounting */
-	atomic_t migration_in_progress;
 	void *snp_context;      /* SNP guest context page */
 	void *guest_req_buf;    /* Bounce buffer for SNP Guest Request input */
 	void *guest_resp_buf;   /* Bounce buffer for SNP Guest Request output */
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 1dedc421b3e3..0c1d637a6e7d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -862,6 +862,7 @@ struct kvm {
 	/* Protected by slots_locks (for writes) and RCU (for reads) */
 	struct xarray mem_attr_array;
 #endif
+	atomic_t migration_in_progress;
 	char stats_id[KVM_STATS_NAME_SIZE];
 };
 
-- 
2.49.0.1101.gccaa498523-goog