From: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
So far we were flushing almost the entire universe whenever a VM would
load/unload the SCTLR_EL1 and the two versions of that register had
different MMU enabled settings. This turned out to be so slow that it
prevented forward progress for a nested VM, because a scheduler timer
tick interrupt would always be pending when we reached the nested VM.
To avoid this problem, we consider the SCTLR_EL2 when evaluating if
caches are on or off when entering virtual EL2 (because this is the
value that we end up shadowing onto the hardware EL1 register).
Reviewed-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: Jintack Lim <jintack.lim@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_mmu.h | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 7f7c1231679e..083cc47dca08 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -115,6 +115,7 @@ alternative_cb_end
#include <asm/cache.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
+#include <asm/kvm_emulate.h>
#include <asm/kvm_host.h>
void kvm_update_va_mask(struct alt_instr *alt,
@@ -192,7 +193,15 @@ struct kvm;
static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu)
{
- return (vcpu_read_sys_reg(vcpu, SCTLR_EL1) & 0b101) == 0b101;
+ u64 cache_bits = SCTLR_ELx_M | SCTLR_ELx_C;
+ int reg;
+
+ if (vcpu_is_el2(vcpu))
+ reg = SCTLR_EL2;
+ else
+ reg = SCTLR_EL1;
+
+ return (vcpu_read_sys_reg(vcpu, reg) & cache_bits) == cache_bits;
}
static inline void __clean_dcache_guest_page(void *va, size_t size)
--
2.34.1
