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| author | Marc Zyngier <maz@kernel.org> | 2023-07-13 08:06:57 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-08-23 17:52:28 +0200 |
| commit | 3d2d051be16115ca930cd2b76b18e54532bf56cd (patch) | |
| tree | 61fc1101bca013b235acc0145eaca2e262203453 /arch/arm64/include | |
| parent | 402f1d86ea26c160841da4eb46b0ad8606ab52b3 (diff) | |
| download | linux-3d2d051be16115ca930cd2b76b18e54532bf56cd.tar.gz | |
KVM: arm64: vgic-v4: Make the doorbell request robust w.r.t preemption
[ Upstream commit b321c31c9b7b309dcde5e8854b741c8e6a9a05f0 ]
Xiang reports that VMs occasionally fail to boot on GICv4.1 systems when
running a preemptible kernel, as it is possible that a vCPU is blocked
without requesting a doorbell interrupt.
The issue is that any preemption that occurs between vgic_v4_put() and
schedule() on the block path will mark the vPE as nonresident and *not*
request a doorbell irq. This occurs because when the vcpu thread is
resumed on its way to block, vcpu_load() will make the vPE resident
again. Once the vcpu actually blocks, we don't request a doorbell
anymore, and the vcpu won't be woken up on interrupt delivery.
Fix it by tracking that we're entering WFI, and key the doorbell
request on that flag. This allows us not to make the vPE resident
when going through a preempt/schedule cycle, meaning we don't lose
any state.
Cc: stable@vger.kernel.org
Fixes: 8e01d9a396e6 ("KVM: arm64: vgic-v4: Move the GICv4 residency flow to be driven by vcpu_load/put")
Reported-by: Xiang Chen <chenxiang66@hisilicon.com>
Suggested-by: Zenghui Yu <yuzenghui@huawei.com>
Tested-by: Xiang Chen <chenxiang66@hisilicon.com>
Co-developed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Zenghui Yu <yuzenghui@huawei.com>
Link: https://lore.kernel.org/r/20230713070657.3873244-1-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/arm64/include')
| -rw-r--r-- | arch/arm64/include/asm/kvm_host.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index b5a8e8b3c691..577cf444c113 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -559,6 +559,8 @@ struct kvm_vcpu_arch { #define SYSREGS_ON_CPU __vcpu_single_flag(sflags, BIT(4)) /* Software step state is Active-pending */ #define DBG_SS_ACTIVE_PENDING __vcpu_single_flag(sflags, BIT(5)) +/* WFI instruction trapped */ +#define IN_WFI __vcpu_single_flag(sflags, BIT(7)) /* Pointer to the vcpu's SVE FFR for sve_{save,load}_state() */ |