| Message ID | 20210323010305.1045293-16-npiggin@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: PPC: Book3S: C-ify the P9 entry/exit code | expand |
On Tue, Mar 23, 2021 at 11:02:34AM +1000, Nicholas Piggin wrote: > System calls / hcalls have a different calling convention than > other interrupts, so there is code in the KVMTEST to massage these > into the same form as other interrupt handlers. > > Move this work into the KVM hcall handler. This means teaching KVM > a little more about the low level interrupt handler setup, PACA save > areas, etc., although that's not obviously worse than the current > approach of coming up with an entirely different interrupt register > / save convention. [snip] > @@ -1964,29 +1948,8 @@ EXC_VIRT_END(system_call, 0x4c00, 0x100) > > #ifdef CONFIG_KVM_BOOK3S_64_HANDLER > TRAMP_REAL_BEGIN(system_call_kvm) > - /* > - * This is a hcall, so register convention is as above, with these > - * differences: I haven't checked all the code changes in detail yet, but this comment at least is slightly misleading, since under PR KVM, system calls (to the guest kernel) and hypercalls both come through this path. Paul.
Excerpts from Paul Mackerras's message of April 1, 2021 3:41 pm: > On Tue, Mar 23, 2021 at 11:02:34AM +1000, Nicholas Piggin wrote: >> System calls / hcalls have a different calling convention than >> other interrupts, so there is code in the KVMTEST to massage these >> into the same form as other interrupt handlers. >> >> Move this work into the KVM hcall handler. This means teaching KVM >> a little more about the low level interrupt handler setup, PACA save >> areas, etc., although that's not obviously worse than the current >> approach of coming up with an entirely different interrupt register >> / save convention. > > [snip] > >> @@ -1964,29 +1948,8 @@ EXC_VIRT_END(system_call, 0x4c00, 0x100) >> >> #ifdef CONFIG_KVM_BOOK3S_64_HANDLER >> TRAMP_REAL_BEGIN(system_call_kvm) >> - /* >> - * This is a hcall, so register convention is as above, with these >> - * differences: > > I haven't checked all the code changes in detail yet, but this comment > at least is slightly misleading, since under PR KVM, system calls (to > the guest kernel) and hypercalls both come through this path. Yeah good point, I'll update the comment at its destination. Thanks, Nick
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h index c1a8aac01cf9..bb6f78fcf981 100644 --- a/arch/powerpc/include/asm/exception-64s.h +++ b/arch/powerpc/include/asm/exception-64s.h @@ -35,6 +35,19 @@ /* PACA save area size in u64 units (exgen, exmc, etc) */ #define EX_SIZE 10 +/* PACA save area offsets */ +#define EX_R9 0 +#define EX_R10 8 +#define EX_R11 16 +#define EX_R12 24 +#define EX_R13 32 +#define EX_DAR 40 +#define EX_DSISR 48 +#define EX_CCR 52 +#define EX_CFAR 56 +#define EX_PPR 64 +#define EX_CTR 72 + /* * maximum recursive depth of MCE exceptions */ diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 98bf73df0f57..a23feaa445b5 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -21,22 +21,6 @@ #include <asm/feature-fixups.h> #include <asm/kup.h> -/* PACA save area offsets (exgen, exmc, etc) */ -#define EX_R9 0 -#define EX_R10 8 -#define EX_R11 16 -#define EX_R12 24 -#define EX_R13 32 -#define EX_DAR 40 -#define EX_DSISR 48 -#define EX_CCR 52 -#define EX_CFAR 56 -#define EX_PPR 64 -#define EX_CTR 72 -.if EX_SIZE != 10 - .error "EX_SIZE is wrong" -.endif - /* * Following are fixed section helper macros. * @@ -1964,29 +1948,8 @@ EXC_VIRT_END(system_call, 0x4c00, 0x100) #ifdef CONFIG_KVM_BOOK3S_64_HANDLER TRAMP_REAL_BEGIN(system_call_kvm) - /* - * This is a hcall, so register convention is as above, with these - * differences: - * r13 = PACA - * ctr = orig r13 - * orig r10 saved in PACA - */ - /* - * Save the PPR (on systems that support it) before changing to - * HMT_MEDIUM. That allows the KVM code to save that value into the - * guest state (it is the guest's PPR value). - */ -BEGIN_FTR_SECTION - mfspr r10,SPRN_PPR - std r10,HSTATE_PPR(r13) -END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) - HMT_MEDIUM mfctr r10 - SET_SCRATCH0(r10) - mfcr r10 - std r12,HSTATE_SCRATCH0(r13) - sldi r12,r10,32 - ori r12,r12,0xc00 + SET_SCRATCH0(r10) /* Save r13 in SCRATCH0 */ #ifdef CONFIG_RELOCATABLE /* * Requires __LOAD_FAR_HANDLER beause kvmppc_hcall lives @@ -1994,15 +1957,12 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) */ __LOAD_FAR_HANDLER(r10, kvmppc_hcall) mtctr r10 - ld r10,PACA_EXGEN+EX_R10(r13) bctr #else - ld r10,PACA_EXGEN+EX_R10(r13) b kvmppc_hcall #endif #endif - /** * Interrupt 0xd00 - Trace Interrupt. * This is a synchronous interrupt in response to instruction step or diff --git a/arch/powerpc/kvm/book3s_64_entry.S b/arch/powerpc/kvm/book3s_64_entry.S index 8cf5e24a81eb..dea8c5bb207b 100644 --- a/arch/powerpc/kvm/book3s_64_entry.S +++ b/arch/powerpc/kvm/book3s_64_entry.S @@ -14,6 +14,29 @@ .global kvmppc_hcall .balign IFETCH_ALIGN_BYTES kvmppc_hcall: + /* + * This is a hcall, so register convention is as + * Documentation/powerpc/papr_hcalls.rst, with these additions: + * R13 = PACA + * guest R13 saved in SPRN_SCRATCH0 + * R10 = free + * guest r10 saved in PACA_EXGEN + */ + /* + * Save the PPR (on systems that support it) before changing to + * HMT_MEDIUM. That allows the KVM code to save that value into the + * guest state (it is the guest's PPR value). + */ +BEGIN_FTR_SECTION + mfspr r10,SPRN_PPR + std r10,HSTATE_PPR(r13) +END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) + HMT_MEDIUM + mfcr r10 + std r12,HSTATE_SCRATCH0(r13) + sldi r12,r10,32 + ori r12,r12,0xc00 + ld r10,PACA_EXGEN+EX_R10(r13) .global kvmppc_interrupt .balign IFETCH_ALIGN_BYTES
System calls / hcalls have a different calling convention than other interrupts, so there is code in the KVMTEST to massage these into the same form as other interrupt handlers. Move this work into the KVM hcall handler. This means teaching KVM a little more about the low level interrupt handler setup, PACA save areas, etc., although that's not obviously worse than the current approach of coming up with an entirely different interrupt register / save convention. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/include/asm/exception-64s.h | 13 ++++++++ arch/powerpc/kernel/exceptions-64s.S | 42 +----------------------- arch/powerpc/kvm/book3s_64_entry.S | 23 +++++++++++++ 3 files changed, 37 insertions(+), 41 deletions(-)