6.1-stable patches

[thirdparty/kernel/stable-queue.git] / queue-6.1 / kvm-svm-warn-but-continue-if-misc_cg_set_capacity-fa.patch

From b438e2cec334ebdf9dc1fef6d41f786d3053c5d5 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Tue, 6 Jun 2023 17:44:49 -0700
Subject: KVM: SVM: WARN, but continue, if misc_cg_set_capacity() fails

From: Sean Christopherson <seanjc@google.com>

[ Upstream commit 106ed2cad9f7bd803bd31a18fe7a9219b077bf95 ]

WARN and continue if misc_cg_set_capacity() fails, as the only scenario
in which it can fail is if the specified resource is invalid, which should
never happen when CONFIG_KVM_AMD_SEV=y.  Deliberately not bailing "fixes"
a theoretical bug where KVM would leak the ASID bitmaps on failure, which
again can't happen.

If the impossible should happen, the end result is effectively the same
with respect to SEV and SEV-ES (they are unusable), while continuing on
has the advantage of letting KVM load, i.e. userspace can still run
non-SEV guests.

Reported-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Link: https://lore.kernel.org/r/20230607004449.1421131-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Stable-dep-of: 0aa6b90ef9d7 ("KVM: SVM: Add support for allowing zero SEV ASIDs")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/svm/sev.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 1fe9257d87b2d..0316fdf5040f7 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2214,9 +2214,7 @@ void __init sev_hardware_setup(void)
 	}
 
 	sev_asid_count = max_sev_asid - min_sev_asid + 1;
-	if (misc_cg_set_capacity(MISC_CG_RES_SEV, sev_asid_count))
-		goto out;
-
+	WARN_ON_ONCE(misc_cg_set_capacity(MISC_CG_RES_SEV, sev_asid_count));
 	sev_supported = true;
 
 	/* SEV-ES support requested? */
@@ -2241,9 +2239,7 @@ void __init sev_hardware_setup(void)
 		goto out;
 
 	sev_es_asid_count = min_sev_asid - 1;
-	if (misc_cg_set_capacity(MISC_CG_RES_SEV_ES, sev_es_asid_count))
-		goto out;
-
+	WARN_ON_ONCE(misc_cg_set_capacity(MISC_CG_RES_SEV_ES, sev_es_asid_count));
 	sev_es_supported = true;
 
 out:
-- 
2.43.0