KVM: MIPS: Use root tlb to control guest's CCA for Loongson-3

KVM guest has two levels of address translation: guest tlb translates
GVA to GPA, and root tlb translates GPA to HPA. By default guest's CCA
is controlled by guest tlb, but Loongson-3 maintains all cache coherency
by hardware (including multi-core coherency and I/O DMA coherency) so it
prefers all guest mappings be cacheable mappings. Thus, we use root tlb
to control guest's CCA for Loongson-3.

Reviewed-by: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Co-developed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-Id: <1590220602-3547-8-git-send-email-chenhc@lemote.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/mips/kvm/vz.c b/arch/mips/kvm/vz.c
index 6e1b380..6e62154 100644 (file)
--- a/arch/mips/kvm/vz.c
+++ b/arch/mips/kvm/vz.c
@@ -2871,6 +2871,12 @@ static int kvm_vz_hardware_enable(void)
        if (cpu_has_guestctl2)
                clear_c0_guestctl2(0x3f << 10);
 
+#ifdef CONFIG_CPU_LOONGSON64
+       /* Control guest CCA attribute */
+       if (cpu_has_csr())
+               csr_writel(csr_readl(0xffffffec) | 0x1, 0xffffffec);
+#endif
+
        return 0;
 }