diff options
| author | Akihiko Odaki <akihiko.odaki@daynix.com> | 2025-03-15 18:12:10 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-04-20 10:17:59 +0200 |
| commit | b63e48b4d2ef052d48fd4e110ecc953dfbfaf0dd (patch) | |
| tree | c1ed9dd9dd41128fcd6add20e503d57ccd99ab81 /arch | |
| parent | a797b4f0ed2be9b21ec06ed359f677a1ca84549d (diff) | |
KVM: arm64: PMU: Set raw values from user to PM{C,I}NTEN{SET,CLR}, PMOVS{SET,CLR}
commit f2aeb7bbd5745fbcf7f0769e29a184e24924b9a9 upstream.
Commit a45f41d754e0 ("KVM: arm64: Add {get,set}_user for
PM{C,I}NTEN{SET,CLR}, PMOVS{SET,CLR}") changed KVM_SET_ONE_REG to update
the mentioned registers in a way matching with the behavior of guest
register writes. This is a breaking change of a UAPI though the new
semantics looks cleaner and VMMs are not prepared for this.
Firecracker, QEMU, and crosvm perform migration by listing registers
with KVM_GET_REG_LIST, getting their values with KVM_GET_ONE_REG and
setting them with KVM_SET_ONE_REG. This algorithm assumes
KVM_SET_ONE_REG restores the values retrieved with KVM_GET_ONE_REG
without any alteration. However, bit operations added by the earlier
commit do not preserve the values retried with KVM_GET_ONE_REG and
potentially break migration.
Remove the bit operations that alter the values retrieved with
KVM_GET_ONE_REG.
Cc: stable@vger.kernel.org
Fixes: a45f41d754e0 ("KVM: arm64: Add {get,set}_user for PM{C,I}NTEN{SET,CLR}, PMOVS{SET,CLR}")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250315-pmc-v5-1-ecee87dab216@daynix.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/kvm/sys_regs.c | 21 |
1 files changed, 2 insertions, 19 deletions
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 634ff18a59a1..6479a1c61326 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1166,26 +1166,9 @@ static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p, static int set_pmreg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r, u64 val) { - bool set; - - val &= kvm_pmu_accessible_counter_mask(vcpu); - - switch (r->reg) { - case PMOVSSET_EL0: - /* CRm[1] being set indicates a SET register, and CLR otherwise */ - set = r->CRm & 2; - break; - default: - /* Op2[0] being set indicates a SET register, and CLR otherwise */ - set = r->Op2 & 1; - break; - } - - if (set) - __vcpu_sys_reg(vcpu, r->reg) |= val; - else - __vcpu_sys_reg(vcpu, r->reg) &= ~val; + u64 mask = kvm_pmu_accessible_counter_mask(vcpu); + __vcpu_sys_reg(vcpu, r->reg) = val & mask; return 0; } |