Re: [PATCH v2 2/2] arch/powerpc/kvm: kvmppc_hv_entry: remove r4 argument
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2023-03-15 04:53:14
Also in:
lkml
Kautuk Consul [off-list ref] writes:
quoted hunk ↗ jump to hunk
kvmppc_hv_entry is called from only 2 locations within book3s_hv_rmhandlers.S. Both of those locations set r4 as HSTATE_KVM_VCPU(r13) before calling kvmppc_hv_entry. So, shift the r4 load instruction to kvmppc_hv_entry and thus modify the calling convention of this function. Signed-off-by: Kautuk Consul <redacted> --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index b81ba4ee0521..da9a15db12fe 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S@@ -85,7 +85,7 @@ _GLOBAL_TOC(kvmppc_hv_entry_trampoline) RFI_TO_KERNEL kvmppc_call_hv_entry: - ld r4, HSTATE_KVM_VCPU(r13) + /* Enter guest. */ bl kvmppc_hv_entry /* Back from guest - restore host state and return to caller */@@ -352,9 +352,7 @@ kvm_secondary_got_guest: mtspr SPRN_LDBAR, r0 isync 63: - /* Order load of vcpu after load of vcore */ - lwsync
Where did this barrier go? I don't see that it's covered by any existing barriers in kvmppc_hv_entry, and you don't add it back anywhere.
quoted hunk ↗ jump to hunk
- ld r4, HSTATE_KVM_VCPU(r13) + /* Enter guest. */ bl kvmppc_hv_entry /* Back from the guest, go back to nap */@@ -506,7 +504,6 @@ SYM_INNER_LABEL(kvmppc_hv_entry, SYM_L_LOCAL) /* Required state: * - * R4 = vcpu pointer (or NULL) * MSR = ~IR|DR * R13 = PACA * R1 = host R1@@ -524,6 +521,8 @@ SYM_INNER_LABEL(kvmppc_hv_entry, SYM_L_LOCAL) li r6, KVM_GUEST_MODE_HOST_HV stb r6, HSTATE_IN_GUEST(r13) + ld r4, HSTATE_KVM_VCPU(r13) + #ifdef CONFIG_KVM_BOOK3S_HV_P8_TIMING /* Store initial timestamp */ cmpdi r4, 0
cheers