From: Michael Ellerman <mpe@ellerman•id.au>
To: Kautuk Consul <kconsul@linux•vnet.ibm.com>,
Nicholas Piggin <npiggin@gmail•com>,
Christophe Leroy <christophe.leroy@csgroup•eu>,
"Naveen N. Rao" <naveen.n.rao@linux•vnet.ibm.com>,
Sathvika Vasireddy <sv@linux•ibm.com>,
Alexey Kardashevskiy <aik@ozlabs•ru>,
Fabiano Rosas <farosas@linux•ibm.com>
Cc: linuxppc-dev@lists•ozlabs.org, linux-kernel@vger•kernel.org,
Kautuk Consul <kconsul@linux•vnet.ibm.com>
Subject: Re: [PATCH v2 2/2] arch/powerpc/kvm: kvmppc_hv_entry: remove r4 argument
Date: Wed, 15 Mar 2023 15:48:53 +1100 [thread overview]
Message-ID: <875yb2oc0a.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20230306123740.3648841-3-kconsul@linux.vnet.ibm.com>
Kautuk Consul <kconsul@linux•vnet.ibm.com> writes:
> 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 <kconsul@linux•vnet.ibm.com>
> ---
> 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.
> - 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
next prev parent reply other threads:[~2023-03-15 4:50 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 12:37 [PATCH v2 0/2] Improving calls to kvmppc_hv_entry Kautuk Consul
2023-03-06 12:37 ` [PATCH v2 1/2] arch/powerpc/kvm: kvmppc_hv_entry: remove .global scope Kautuk Consul
2023-03-06 12:37 ` [PATCH v2 2/2] arch/powerpc/kvm: kvmppc_hv_entry: remove r4 argument Kautuk Consul
2023-03-15 4:48 ` Michael Ellerman [this message]
2023-03-15 5:17 ` Kautuk Consul
2023-03-15 5:37 ` Kautuk Consul
2023-03-16 3:39 ` Michael Ellerman
2023-03-16 3:40 ` Michael Ellerman
2023-03-16 3:49 ` Kautuk Consul
2023-03-13 5:39 ` [PATCH v2 0/2] Improving calls to kvmppc_hv_entry Kautuk Consul
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