lkml.org 
[lkml]   [2019]   [Aug]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC PATCH v2 07/19] RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls
From
Date
On 02/08/19 09:47, Anup Patel wrote:
> + if (reg_num == KVM_REG_RISCV_CSR_REG(sip))
> + kvm_riscv_vcpu_flush_interrupts(vcpu, false);

Not updating the vsip CSR here can cause an interrupt to be lost, if the
next call to kvm_riscv_vcpu_flush_interrupts finds a zero mask.

You could add a new field vcpu->vsip_shadow that is updated every time
CSR_VSIP is written (including kvm_arch_vcpu_load) with a function like

void kvm_riscv_update_vsip(struct kvm_vcpu *vcpu)
{
if (vcpu->vsip_shadow != vcpu->arch.guest_csr.vsip) {
csr_write(CSR_VSIP, vcpu->arch.guest_csr.vsip);
vcpu->vsip_shadow = vcpu->arch.guest_csr.vsip;
}
}

And just call this unconditionally from kvm_vcpu_ioctl_run. The cost is
just a memory load per VS-mode entry, it should hardly be measurable.

Paolo

\
 
 \ /
  Last update: 2019-08-02 11:04    [W:0.208 / U:0.100 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site