KVM: PPC: Book3S: Change interrupt call to reduce scratch space use on HV

Change the calling convention to put the trap number together with
CR in two halves of r12, which frees up HSTATE_SCRATCH2 in the HV
handler.

The 64-bit PR handler entry translates the calling convention back
to match the previous call convention (i.e., shared with 32-bit), for
simplicity.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 9a3eee66129766d84d8bd5063fd8ecd142e8fc21..a02a268bde6bf0f9a271567f430c70b56cfb4cca 100644 (file)
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -233,7 +233,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
 
 #endif
 
-#define __KVM_HANDLER_PROLOG(area, n)                                  \
+#define __KVM_HANDLER(area, h, n)                                      \
        BEGIN_FTR_SECTION_NESTED(947)                                   \
        ld      r10,area+EX_CFAR(r13);                                  \
        std     r10,HSTATE_CFAR(r13);                                   \
@@ -243,30 +243,28 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
        std     r10,HSTATE_PPR(r13);                                    \
        END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,948);    \
        ld      r10,area+EX_R10(r13);                                   \
-       stw     r9,HSTATE_SCRATCH1(r13);                                \
-       ld      r9,area+EX_R9(r13);                                     \
        std     r12,HSTATE_SCRATCH0(r13);                               \
-
-#define __KVM_HANDLER(area, h, n)                                      \
-       __KVM_HANDLER_PROLOG(area, n)                                   \
-       li      r12,n;                                                  \
+       sldi    r12,r9,32;                                              \
+       ori     r12,r12,(n);                                            \
+       ld      r9,area+EX_R9(r13);                                     \
        b       kvmppc_interrupt
 
 #define __KVM_HANDLER_SKIP(area, h, n)                                 \
        cmpwi   r10,KVM_GUEST_MODE_SKIP;                                \
-       ld      r10,area+EX_R10(r13);                                   \
        beq     89f;                                                    \
-       stw     r9,HSTATE_SCRATCH1(r13);                                \
        BEGIN_FTR_SECTION_NESTED(948)                                   \
-       ld      r9,area+EX_PPR(r13);                                    \
-       std     r9,HSTATE_PPR(r13);                                     \
+       ld      r10,area+EX_PPR(r13);                                   \
+       std     r10,HSTATE_PPR(r13);                                    \
        END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,948);    \
-       ld      r9,area+EX_R9(r13);                                     \
+       ld      r10,area+EX_R10(r13);                                   \
        std     r12,HSTATE_SCRATCH0(r13);                               \
-       li      r12,n;                                                  \
+       sldi    r12,r9,32;                                              \
+       ori     r12,r12,(n);                                            \
+       ld      r9,area+EX_R9(r13);                                     \
        b       kvmppc_interrupt;                                       \
 89:    mtocrf  0x80,r9;                                                \
        ld      r9,area+EX_R9(r13);                                     \
+       ld      r10,area+EX_R10(r13);                                   \
        b       kvmppc_skip_##h##interrupt
 
 #ifdef CONFIG_KVM_BOOK3S_64_HANDLER

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 9338a818e05cf8a7285471bca75cad2c8c2a7a46..11882aac8216f8e3f860fb10f3f0fd97f2d40b80 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1057,19 +1057,18 @@ hdec_soon:
 kvmppc_interrupt_hv:
        /*
         * Register contents:
-        * R12          = interrupt vector
+        * R12          = (guest CR << 32) | interrupt vector
         * R13          = PACA
-        * guest CR, R12 saved in shadow VCPU SCRATCH1/0
+        * guest R12 saved in shadow VCPU SCRATCH0
         * guest R13 saved in SPRN_SCRATCH0
         */
-       std     r9, HSTATE_SCRATCH2(r13)
-
+       std     r9, HSTATE_SCRATCH1(r13)
        lbz     r9, HSTATE_IN_GUEST(r13)
        cmpwi   r9, KVM_GUEST_MODE_HOST_HV
        beq     kvmppc_bad_host_intr
 #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
        cmpwi   r9, KVM_GUEST_MODE_GUEST
-       ld      r9, HSTATE_SCRATCH2(r13)
+       ld      r9, HSTATE_SCRATCH1(r13)
        beq     kvmppc_interrupt_pr
 #endif
        /* We're now back in the host but in guest MMU context */
@@ -1089,13 +1088,14 @@ kvmppc_interrupt_hv:
        std     r6, VCPU_GPR(R6)(r9)
        std     r7, VCPU_GPR(R7)(r9)
        std     r8, VCPU_GPR(R8)(r9)
-       ld      r0, HSTATE_SCRATCH2(r13)
+       ld      r0, HSTATE_SCRATCH1(r13)
        std     r0, VCPU_GPR(R9)(r9)
        std     r10, VCPU_GPR(R10)(r9)
        std     r11, VCPU_GPR(R11)(r9)
        ld      r3, HSTATE_SCRATCH0(r13)
-       lwz     r4, HSTATE_SCRATCH1(r13)
        std     r3, VCPU_GPR(R12)(r9)
+       /* CR is in the high half of r12 */
+       srdi    r4, r12, 32
        stw     r4, VCPU_CR(r9)
 BEGIN_FTR_SECTION
        ld      r3, HSTATE_CFAR(r13)
@@ -1114,6 +1114,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
        mfspr   r11, SPRN_SRR1
        std     r10, VCPU_SRR0(r9)
        std     r11, VCPU_SRR1(r9)
+       /* trap is in the low half of r12, clear CR from the high half */
+       clrldi  r12, r12, 32
        andi.   r0, r12, 2              /* need to read HSRR0/1? */
        beq     1f
        mfspr   r10, SPRN_HSRR0

diff --git a/arch/powerpc/kvm/book3s_segment.S b/arch/powerpc/kvm/book3s_segment.S
index ca8f174289bb43a148bdd9159f71ca645e0c416a..68e45080cf93d544d56f81161ddd80e519e05813 100644 (file)
--- a/arch/powerpc/kvm/book3s_segment.S
+++ b/arch/powerpc/kvm/book3s_segment.S
@@ -167,20 +167,31 @@ kvmppc_handler_trampoline_enter_end:
  *                                                                            *
  *****************************************************************************/
 
-.global kvmppc_handler_trampoline_exit
-kvmppc_handler_trampoline_exit:
-
 .global kvmppc_interrupt_pr
 kvmppc_interrupt_pr:
+       /* 64-bit entry. Register usage at this point:
+        *
+        * SPRG_SCRATCH0   = guest R13
+        * R12             = (guest CR << 32) | exit handler id
+        * R13             = PACA
+        * HSTATE.SCRATCH0 = guest R12
+        */
+#ifdef CONFIG_PPC64
+       /* Match 32-bit entry */
+       rotldi  r12, r12, 32              /* Flip R12 halves for stw */
+       stw     r12, HSTATE_SCRATCH1(r13) /* CR is now in the low half */
+       srdi    r12, r12, 32              /* shift trap into low half */
+#endif
 
+.global kvmppc_handler_trampoline_exit
+kvmppc_handler_trampoline_exit:
        /* Register usage at this point:
         *
-        * SPRG_SCRATCH0  = guest R13
-        * R12            = exit handler id
-        * R13            = shadow vcpu (32-bit) or PACA (64-bit)
+        * SPRG_SCRATCH0   = guest R13
+        * R12             = exit handler id
+        * R13             = shadow vcpu (32-bit) or PACA (64-bit)
         * HSTATE.SCRATCH0 = guest R12
         * HSTATE.SCRATCH1 = guest CR
-        *
         */
 
        /* Save registers */