| Message ID | 1455127752-17293-2-git-send-email-thuth@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Feb 10, 2016 at 07:09:09PM +0100, Thomas Huth wrote: > This is a very simple hypercall that only sets up the SPRG0 > register for the guest (since writing to SPRG0 was only permitted > to the hypervisor in older versions of the PowerISA). > > Signed-off-by: Thomas Huth <thuth@redhat.com> > --- > hw/ppc/spapr_hcall.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c > index 12f8c33..58103ef 100644 > --- a/hw/ppc/spapr_hcall.c > +++ b/hw/ppc/spapr_hcall.c > @@ -332,6 +332,15 @@ static target_ulong h_read(PowerPCCPU *cpu, sPAPRMachineState *spapr, > return H_SUCCESS; > } > > +static target_ulong h_set_sprg0(PowerPCCPU *cpu, sPAPRMachineState *spapr, > + target_ulong opcode, target_ulong *args) > +{ > + CPUState *cs = CPU(cpu); > + > + set_spr(cs, SPR_SPRG0, args[0], -1L); This looks correct, but I think set_spr() is serious overkill here. It does some fancy synchronization designed for setting one cpu's SPR from an hcall executed on a different CPU. In this case the calling CPU is just setting its own SPRG0, so just cpu_synchronize_state() env->spr[SPR_SPRG0] = XXX Should be sufficient. > + return H_SUCCESS; > +} > + > static target_ulong h_set_dabr(PowerPCCPU *cpu, sPAPRMachineState *spapr, > target_ulong opcode, target_ulong *args) > { > @@ -997,6 +1006,10 @@ static void hypercall_register_types(void) > spapr_register_hypercall(H_REGISTER_VPA, h_register_vpa); > spapr_register_hypercall(H_CEDE, h_cede); > > + /* processor register resource access h-calls */ > + spapr_register_hypercall(H_SET_SPRG0, h_set_sprg0); > + spapr_register_hypercall(H_SET_MODE, h_set_mode); > + > /* "debugger" hcalls (also used by SLOF). Note: We do -not- differenciate > * here between the "CI" and the "CACHE" variants, they will use whatever > * mapping attributes qemu is using. When using KVM, the kernel will > @@ -1013,8 +1026,6 @@ static void hypercall_register_types(void) > /* qemu/KVM-PPC specific hcalls */ > spapr_register_hypercall(KVMPPC_H_RTAS, h_rtas); > > - spapr_register_hypercall(H_SET_MODE, h_set_mode); > - > /* ibm,client-architecture-support support */ > spapr_register_hypercall(KVMPPC_H_CAS, h_client_architecture_support); > }
On 11.02.2016 00:30, David Gibson wrote: > On Wed, Feb 10, 2016 at 07:09:09PM +0100, Thomas Huth wrote: >> This is a very simple hypercall that only sets up the SPRG0 >> register for the guest (since writing to SPRG0 was only permitted >> to the hypervisor in older versions of the PowerISA). >> >> Signed-off-by: Thomas Huth <thuth@redhat.com> >> --- >> hw/ppc/spapr_hcall.c | 15 +++++++++++++-- >> 1 file changed, 13 insertions(+), 2 deletions(-) >> >> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c >> index 12f8c33..58103ef 100644 >> --- a/hw/ppc/spapr_hcall.c >> +++ b/hw/ppc/spapr_hcall.c >> @@ -332,6 +332,15 @@ static target_ulong h_read(PowerPCCPU *cpu, sPAPRMachineState *spapr, >> return H_SUCCESS; >> } >> >> +static target_ulong h_set_sprg0(PowerPCCPU *cpu, sPAPRMachineState *spapr, >> + target_ulong opcode, target_ulong *args) >> +{ >> + CPUState *cs = CPU(cpu); >> + >> + set_spr(cs, SPR_SPRG0, args[0], -1L); > > This looks correct, but I think set_spr() is serious overkill here. > It does some fancy synchronization designed for setting one cpu's SPR > from an hcall executed on a different CPU. In this case the calling > CPU is just setting its own SPRG0, so just > cpu_synchronize_state() > env->spr[SPR_SPRG0] = XXX > > Should be sufficient. AFAIK the synchronization stuff is skipped when set_spr() runs already on the destination CPU, but ok, since h-calls should be fast, I can change this anyway to save some precious cycles. Thomas
diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c index 12f8c33..58103ef 100644 --- a/hw/ppc/spapr_hcall.c +++ b/hw/ppc/spapr_hcall.c @@ -332,6 +332,15 @@ static target_ulong h_read(PowerPCCPU *cpu, sPAPRMachineState *spapr, return H_SUCCESS; } +static target_ulong h_set_sprg0(PowerPCCPU *cpu, sPAPRMachineState *spapr, + target_ulong opcode, target_ulong *args) +{ + CPUState *cs = CPU(cpu); + + set_spr(cs, SPR_SPRG0, args[0], -1L); + return H_SUCCESS; +} + static target_ulong h_set_dabr(PowerPCCPU *cpu, sPAPRMachineState *spapr, target_ulong opcode, target_ulong *args) { @@ -997,6 +1006,10 @@ static void hypercall_register_types(void) spapr_register_hypercall(H_REGISTER_VPA, h_register_vpa); spapr_register_hypercall(H_CEDE, h_cede); + /* processor register resource access h-calls */ + spapr_register_hypercall(H_SET_SPRG0, h_set_sprg0); + spapr_register_hypercall(H_SET_MODE, h_set_mode); + /* "debugger" hcalls (also used by SLOF). Note: We do -not- differenciate * here between the "CI" and the "CACHE" variants, they will use whatever * mapping attributes qemu is using. When using KVM, the kernel will @@ -1013,8 +1026,6 @@ static void hypercall_register_types(void) /* qemu/KVM-PPC specific hcalls */ spapr_register_hypercall(KVMPPC_H_RTAS, h_rtas); - spapr_register_hypercall(H_SET_MODE, h_set_mode); - /* ibm,client-architecture-support support */ spapr_register_hypercall(KVMPPC_H_CAS, h_client_architecture_support); }
This is a very simple hypercall that only sets up the SPRG0 register for the guest (since writing to SPRG0 was only permitted to the hypervisor in older versions of the PowerISA). Signed-off-by: Thomas Huth <thuth@redhat.com> --- hw/ppc/spapr_hcall.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)