linux-kernel - [PATCH 4/5] KVM: SVM: Convert DEACTIVATE mutex to read/write semaphore

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Date:   Thu, 3 Oct 2019 21:17:47 +0000
From:   "Lendacky, Thomas" <Thomas.Lendacky@....com>
To:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        "Singh, Brijesh" <brijesh.singh@....com>,
        David Rientjes <rientjes@...gle.com>
Subject: [PATCH 4/5] KVM: SVM: Convert DEACTIVATE mutex to read/write
 semaphore

From: Tom Lendacky <thomas.lendacky@....com>

In preparation for an upcoming patch, convert the mutex that guards the
DEACTIVATE/WBINVD/DF_FLUSH sequence into a read/write semaphore. The
conversion will convert the mutex lock and unlock into down_write and
up_write so that the mutex behavior is maintained.

Tested-by: David Rientjes <rientjes@...gle.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kvm/svm.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 389dfd7594eb..b995d7ac1516 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -38,6 +38,7 @@
 #include <linux/file.h>
 #include <linux/pagemap.h>
 #include <linux/swap.h>
+#include <linux/rwsem.h>
 
 #include <asm/apic.h>
 #include <asm/perf_event.h>
@@ -418,7 +419,7 @@ enum {
 
 #define VMCB_AVIC_APIC_BAR_MASK		0xFFFFFFFFFF000ULL
 
-static DEFINE_MUTEX(sev_deactivate_lock);
+static DECLARE_RWSEM(sev_deactivate_lock);
 static DEFINE_MUTEX(sev_bitmap_lock);
 static unsigned int max_sev_asid;
 static unsigned int min_sev_asid;
@@ -1762,14 +1763,14 @@ static void sev_unbind_asid(struct kvm *kvm, unsigned int handle)
 	 * Guard against a parallel DEACTIVATE command before the DF_FLUSH
 	 * command has completed.
 	 */
-	mutex_lock(&sev_deactivate_lock);
+	down_write(&sev_deactivate_lock);
 
 	sev_guest_deactivate(data, NULL);
 
 	wbinvd_on_all_cpus();
 	sev_guest_df_flush(NULL);
 
-	mutex_unlock(&sev_deactivate_lock);
+	up_write(&sev_deactivate_lock);
 
 	kfree(data);
 
-- 
2.17.1