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KVM: SVM: WARN, but continue, if misc_cg_set_capacity() fails

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[ Upstream commit 106ed2cad9 ]

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: 0aa6b90ef9 ("KVM: SVM: Add support for allowing zero SEV ASIDs")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Sean Christopherson
2023-06-06 17:44:49 -07:00
committed by Greg Kroah-Hartman
parent 2f7efda53a
commit 815c2a1c43
1 changed files with 2 additions and 6 deletions
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arch/x86/kvm/svm/sev.c
+2 -6
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@@ -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: