[RFC 16/48] RISC-V: KVM: Skip most VCPU requests for TVMs

From: Atish Patra
Date: Wed Apr 19 2023 - 18:19:20 EST


Currently, KVM manages TLB shootdown, hgatp updates and
fence.i through vcpu requests.

TLB shootdown for the TVMs happens in co-ordination with TSM.
The fence.i & hgatp updates are directly managed by the TSM.
There is no need to issue these requests directly for TVMs.

Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx>
---
arch/riscv/kvm/vcpu.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index c53bf98..3b600c6 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -22,6 +22,7 @@
#include <asm/kvm_nacl.h>
#include <asm/hwcap.h>
#include <asm/sbi.h>
+#include <asm/kvm_cove.h>

const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
KVM_GENERIC_VCPU_STATS(),
@@ -1078,6 +1079,15 @@ static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
if (kvm_check_request(KVM_REQ_VCPU_RESET, vcpu))
kvm_riscv_reset_vcpu(vcpu);

+ if (is_cove_vcpu(vcpu)) {
+ /*
+ * KVM doesn't need to do anything special here
+ * as the TSM is expected track the tlb version and issue
+ * hfence when vcpu is scheduled again.
+ */
+ return;
+ }
+
if (kvm_check_request(KVM_REQ_UPDATE_HGATP, vcpu))
kvm_riscv_gstage_update_hgatp(vcpu);

--
2.25.1