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UPSTREAM: KVM: arm64: Fix CPU interface MMIO compatibility detection

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In order to detect whether a GICv3 CPU interface is MMIO capable,
we switch ICC_SRE_EL1.SRE to 0 and check whether it sticks.

However, this is only possible if *ALL* of the HCR_EL2 interrupt
overrides are set, and the CPU is perfectly allowed to ignore
the write to ICC_SRE_EL1 otherwise. This leads KVM to pretend
that a whole bunch of ARMv8.0 CPUs aren't MMIO-capable, and
breaks VMs that should work correctly otherwise.

Fix this by setting IMO/FMO/IMO before touching ICC_SRE_EL1,
and clear them afterwards. This allows us to reliably detect
the CPU interface capabilities.

Tested-by: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
Fixes: 9739f6ef05 ("KVM: arm64: Workaround firmware wrongly advertising GICv2-on-v3 compatibility")
Signed-off-by: Marc Zyngier <maz@kernel.org>
(cherry picked from commit af22df997d)
Bug: 178098380
Signed-off-by: Will Deacon <willdeacon@google.com>
Change-Id: I188304844d50de9e47a0634e0b0179ca96cbf275
This commit is contained in:
Marc Zyngier
2021-03-23 16:08:18 +00:00
committed by Will Deacon
parent 52840dfa57
commit 73be6141e9
1 changed files with 9 additions and 0 deletions
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9
arch/arm64/kvm/hyp/vgic-v3-sr.c
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@@ -429,6 +429,13 @@ u64 __vgic_v3_get_gic_config(void)
if (has_vhe())
flags = local_daif_save();
/*
* Table 11-2 "Permitted ICC_SRE_ELx.SRE settings" indicates
* that to be able to set ICC_SRE_EL1.SRE to 0, all the
* interrupt overrides must be set. You've got to love this.
*/
sysreg_clear_set(hcr_el2, 0, HCR_AMO | HCR_FMO | HCR_IMO);
isb();
write_gicreg(0, ICC_SRE_EL1);
isb();
@@ -436,6 +443,8 @@ u64 __vgic_v3_get_gic_config(void)
write_gicreg(sre, ICC_SRE_EL1);
isb();
sysreg_clear_set(hcr_el2, HCR_AMO | HCR_FMO | HCR_IMO, 0);
isb();
if (has_vhe())
local_daif_restore(flags);