The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x f6da81f650fa47b61b847488f3938d43f90d093d # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023040310-snowbird-bacteria-e989@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

f6da81f650fa ("KVM: arm64: PMU: Don't save PMCR_EL0.{C,P} for the vCPU") 64d6820d64c0 ("KVM: arm64: PMU: Sanitise PMCR_EL0.LP on first vcpu run") 11af4c37165e ("KVM: arm64: PMU: Implement PMUv3p5 long counter support") 3d0dba5764b9 ("KVM: arm64: PMU: Move the ID_AA64DFR0_EL1.PMUver limit to VM creation") c82d28cbf1d4 ("KVM: arm64: PMU: Distinguish between 64bit counter and 64bit overflow") bead02204e98 ("KVM: arm64: PMU: Align chained counter implementation with architecture pseudocode") 121a8fc088f1 ("arm64/sysreg: Use feature numbering for PMU and SPE revisions") fcf37b38ff22 ("arm64/sysreg: Add _EL1 into ID_AA64DFR0_EL1 definition names") c0357a73fa4a ("arm64/sysreg: Align field names in ID_AA64DFR0_EL1 with architecture") 8794b4f510f7 ("Merge branch kvm-arm64/per-vcpu-host-pmu-data into kvmarm-master/next")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f6da81f650fa47b61b847488f3938d43f90d093d Mon Sep 17 00:00:00 2001 From: Reiji Watanabe reijiw@google.com Date: Sun, 12 Mar 2023 20:32:34 -0700 Subject: [PATCH] KVM: arm64: PMU: Don't save PMCR_EL0.{C,P} for the vCPU

Presently, when a guest writes 1 to PMCR_EL0.{C,P}, which is WO/RAZ, KVM saves the register value, including these bits. When userspace reads the register using KVM_GET_ONE_REG, KVM returns the saved register value as it is (the saved value might have these bits set). This could result in userspace setting these bits on the destination during migration. Consequently, KVM may end up resetting the vPMU counter registers (PMCCNTR_EL0 and/or PMEVCNTR<n>_EL0) to zero on the first KVM_RUN after migration.

Fix this by not saving those bits when a guest writes 1 to those bits.

Fixes: ab9468340d2b ("arm64: KVM: Add access handler for PMCR register") Cc: stable@vger.kernel.org Reviewed-by: Marc Zyngier maz@kernel.org Signed-off-by: Reiji Watanabe reijiw@google.com Link: https://lore.kernel.org/r/20230313033234.1475987-1-reijiw@google.com Signed-off-by: Oliver Upton oliver.upton@linux.dev

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c index 24908400e190..c243b10f3e15 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -538,7 +538,8 @@ void kvm_pmu_handle_pmcr(struct kvm_vcpu *vcpu, u64 val) if (!kvm_pmu_is_3p5(vcpu)) val &= ~ARMV8_PMU_PMCR_LP;

- __vcpu_sys_reg(vcpu, PMCR_EL0) = val; + /* The reset bits don't indicate any state, and shouldn't be saved. */ + __vcpu_sys_reg(vcpu, PMCR_EL0) = val & ~(ARMV8_PMU_PMCR_C | ARMV8_PMU_PMCR_P);

if (val & ARMV8_PMU_PMCR_E) { kvm_pmu_enable_counter_mask(vcpu,