On 2020-05-28 13:36, Marc Zyngier wrote:
On 2020-05-26 17:18, James Morse wrote:
KVM sets HCR_EL2.TACR (which it calls HCR_TAC) via HCR_GUEST_FLAGS.
TAC is a leftover from 32bit.
This means ACTLR* accesses from the guest are always trapped, and
always return the value in the sys_regs array.
The guest can't change the value of these registers, so we are
save restoring the reset value, which came from the host.
Stop save/restoring this register.
This also stops this register being affected by sysregs_loaded_on_cpu,
so we can provide 32 bit accessors that always use the in-memory copy.
Signed-off-by: James Morse <[email protected]>
---
arch/arm64/kvm/hyp/sysreg-sr.c | 2 --
arch/arm64/kvm/sys_regs.c | 2 --
2 files changed, 4 deletions(-)
diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c
b/arch/arm64/kvm/hyp/sysreg-sr.c
index 75b1925763f1..57116cf3a1a5 100644
--- a/arch/arm64/kvm/hyp/sysreg-sr.c
+++ b/arch/arm64/kvm/hyp/sysreg-sr.c
@@ -44,7 +44,6 @@ static void __hyp_text
__sysreg_save_el1_state(struct kvm_cpu_context *ctxt)
{
ctxt->sys_regs[CSSELR_EL1] = read_sysreg(csselr_el1);
ctxt->sys_regs[SCTLR_EL1] = read_sysreg_el1(SYS_SCTLR);
- ctxt->sys_regs[ACTLR_EL1] = read_sysreg(actlr_el1);
ctxt->sys_regs[CPACR_EL1] = read_sysreg_el1(SYS_CPACR);
ctxt->sys_regs[TTBR0_EL1] = read_sysreg_el1(SYS_TTBR0);
ctxt->sys_regs[TTBR1_EL1] = read_sysreg_el1(SYS_TTBR1);
@@ -133,7 +132,6 @@ static void __hyp_text
__sysreg_restore_el1_state(struct kvm_cpu_context *ctxt)
isb();
}
- write_sysreg(ctxt->sys_regs[ACTLR_EL1], actlr_el1);
If we don't need to save/restore it, we can also drop its presence
in the sys_regs array.
write_sysreg_el1(ctxt->sys_regs[CPACR_EL1], SYS_CPACR);
write_sysreg_el1(ctxt->sys_regs[TTBR0_EL1], SYS_TTBR0);
write_sysreg_el1(ctxt->sys_regs[TTBR1_EL1], SYS_TTBR1);
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 2eda539f3281..aae58513025c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -81,7 +81,6 @@ u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu,
int reg)
switch (reg) {
case CSSELR_EL1: return read_sysreg_s(SYS_CSSELR_EL1);
case SCTLR_EL1: return read_sysreg_s(SYS_SCTLR_EL12);
- case ACTLR_EL1: return read_sysreg_s(SYS_ACTLR_EL1);
case CPACR_EL1: return read_sysreg_s(SYS_CPACR_EL12);
case TTBR0_EL1: return read_sysreg_s(SYS_TTBR0_EL12);
case TTBR1_EL1: return read_sysreg_s(SYS_TTBR1_EL12);
@@ -124,7 +123,6 @@ void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64
val, int reg)
switch (reg) {
case CSSELR_EL1: write_sysreg_s(val, SYS_CSSELR_EL1); return;
case SCTLR_EL1: write_sysreg_s(val, SYS_SCTLR_EL12); return;
- case ACTLR_EL1: write_sysreg_s(val, SYS_ACTLR_EL1); return;
case CPACR_EL1: write_sysreg_s(val, SYS_CPACR_EL12); return;
case TTBR0_EL1: write_sysreg_s(val, SYS_TTBR0_EL12); return;
case TTBR1_EL1: write_sysreg_s(val, SYS_TTBR1_EL12); return;
It strikes me that we don't even have a trap handler for this sysreg,
whether it is 32 or 64bit... That's a bit unfortunate, to say the
least...
Ah, no. the sucker is hidden away in "generic_v8"...
M.
--
Jazz is not dead. It just smells funny...
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