As promised on the list [0], this series aims to backport 3 upstream
commits [1,2,3] into 5.12-stable tree.
Patch #1 is already in the queue and therefore not included. Patch #2 can
be applied now by manually adding the __KVM_HOST_SMCCC_FUNC___kvm_adjust_pc
macro (please review). Patch #3 can be applied cleanly then (after #2).
I've slightly tested it on my 920 (boot test and the whole kvm-unit-tests),
on top of the latest linux-stable-rc/linux-5.12.y. Please consider taking
them for 5.12-stable.
[0] https://lore.kernel.org/r/[email protected]
[1] https://git.kernel.org/torvalds/c/f5e30680616a
[2] https://git.kernel.org/torvalds/c/26778aaa134a
[3] https://git.kernel.org/torvalds/c/e3e880bb1518
Marc Zyngier (1):
KVM: arm64: Commit pending PC adjustemnts before returning to
userspace
Zenghui Yu (1):
KVM: arm64: Resolve all pending PC updates before immediate exit
arch/arm64/include/asm/kvm_asm.h | 1 +
arch/arm64/kvm/arm.c | 20 +++++++++++++++++---
arch/arm64/kvm/hyp/exception.c | 4 ++--
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 8 ++++++++
4 files changed, 28 insertions(+), 5 deletions(-)
--
2.19.1
commit e3e880bb1518eb10a4b4bb4344ed614d6856f190 upstream.
Commit 26778aaa134a ("KVM: arm64: Commit pending PC adjustemnts before
returning to userspace") fixed the PC updating issue by forcing an explicit
synchronisation of the exception state on vcpu exit to userspace.
However, we forgot to take into account the case where immediate_exit is
set by userspace and KVM_RUN will exit immediately. Fix it by resolving all
pending PC updates before returning to userspace.
Since __kvm_adjust_pc() relies on a loaded vcpu context, I moved the
immediate_exit checking right after vcpu_load(). We will get some overhead
if immediate_exit is true (which should hopefully be rare).
Fixes: 26778aaa134a ("KVM: arm64: Commit pending PC adjustemnts before returning to userspace")
Signed-off-by: Zenghui Yu <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Cc: [email protected] # 5.11
---
arch/arm64/kvm/arm.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index c18740a1e541..7730b81aad6d 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -715,11 +715,13 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
return ret;
}
- if (run->immediate_exit)
- return -EINTR;
-
vcpu_load(vcpu);
+ if (run->immediate_exit) {
+ ret = -EINTR;
+ goto out;
+ }
+
kvm_sigset_activate(vcpu);
ret = 1;
@@ -892,6 +894,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
kvm_sigset_deactivate(vcpu);
+out:
/*
* In the unlikely event that we are returning to userspace
* with pending exceptions or PC adjustment, commit these
--
2.19.1
On Tue, 01 Jun 2021 12:12:38 +0100,
Zenghui Yu <[email protected]> wrote:
>
> commit e3e880bb1518eb10a4b4bb4344ed614d6856f190 upstream.
>
> Commit 26778aaa134a ("KVM: arm64: Commit pending PC adjustemnts before
> returning to userspace") fixed the PC updating issue by forcing an explicit
> synchronisation of the exception state on vcpu exit to userspace.
>
> However, we forgot to take into account the case where immediate_exit is
> set by userspace and KVM_RUN will exit immediately. Fix it by resolving all
> pending PC updates before returning to userspace.
>
> Since __kvm_adjust_pc() relies on a loaded vcpu context, I moved the
> immediate_exit checking right after vcpu_load(). We will get some overhead
> if immediate_exit is true (which should hopefully be rare).
>
> Fixes: 26778aaa134a ("KVM: arm64: Commit pending PC adjustemnts before returning to userspace")
> Signed-off-by: Zenghui Yu <[email protected]>
> Signed-off-by: Marc Zyngier <[email protected]>
> Link: https://lore.kernel.org/r/[email protected]
> Cc: [email protected] # 5.11
Reviewed-by: Marc Zyngier <[email protected]>
M.
--
Without deviation from the norm, progress is not possible.