KVM: PPC: Book3S HV: Allow guest exit path to have MMU on

BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1675806
If we allow LPCR[AIL] to be set for radix guests, then interrupts from
the guest to the host can be delivered by the hardware with relocation
on, and thus the code path starting at kvmppc_interrupt_hv can be
executed in virtual mode (MMU on) for radix guests (previously it was
only ever executed in real mode).

Most of the code is indifferent to whether the MMU is on or off, but
the calls to OPAL that use the real-mode OPAL entry code need to
be switched to use the virtual-mode code instead.  The affected
calls are the calls to the OPAL XICS emulation functions in
kvmppc_read_one_intr() and related functions.  We test the MSR[IR]
bit to detect whether we are in real or virtual mode, and call the
opal_rm_* or opal_* function as appropriate.

The other place that depends on the MMU being off is the optimization
where the guest exit code jumps to the external interrupt vector or
hypervisor doorbell interrupt vector, or returns to its caller (which
is __kvmppc_vcore_entry).  If the MMU is on and we are returning to
the caller, then we don't need to use an rfid instruction since the
MMU is already on; a simple blr suffices.  If there is an external
or hypervisor doorbell interrupt to handle, we branch to the
relocation-on version of the interrupt vector.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit 53af3ba2e8195f504d6a3a0667ccb5e7d4c57599)
Signed-off-by: Breno Leitao <breno.leitao@gmail.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
index 5bb24be0b346c0d39560b16722002e6e6cbb85a3..fe08fea54b70df8db7ab60d62e5bc7f1515406b2 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv_builtin.c
+++ b/arch/powerpc/kvm/book3s_hv_builtin.c
@@ -29,6 +29,11 @@
 #include <asm/opal.h>
 #include <asm/smp.h>
 
+static bool in_realmode(void)
+{
+       return !(mfmsr() & MSR_IR);
+}
+
 #define KVM_CMA_CHUNK_ORDER    18
 
 /*
@@ -200,7 +205,6 @@ static inline void rm_writeb(unsigned long paddr, u8 val)
 
 /*
  * Send an interrupt or message to another CPU.
- * This can only be called in real mode.
  * The caller needs to include any barrier needed to order writes
  * to memory vs. the IPI/message.
  */
@@ -226,7 +230,9 @@ void kvmhv_rm_send_ipi(int cpu)
 
        /* Else poke the target with an IPI */
        xics_phys = paca[cpu].kvm_hstate.xics_phys;
-       if (xics_phys)
+       if (!in_realmode())
+               opal_int_set_mfrr(get_hard_smp_processor_id(cpu), IPI_PRIORITY);
+       else if (xics_phys)
                rm_writeb(xics_phys + XICS_MFRR, IPI_PRIORITY);
        else
                opal_rm_int_set_mfrr(get_hard_smp_processor_id(cpu),
@@ -412,14 +418,15 @@ static long kvmppc_read_one_intr(bool *again)
 
        /* Now read the interrupt from the ICP */
        xics_phys = local_paca->kvm_hstate.xics_phys;
-       if (!xics_phys) {
-               /* Use OPAL to read the XIRR */
+       rc = 0;
+       if (!in_realmode())
+               rc = opal_int_get_xirr(&xirr, false);
+       else if (!xics_phys)
                rc = opal_rm_int_get_xirr(&xirr, false);
-               if (rc < 0)
-                       return 1;
-       } else {
+       else
                xirr = _lwzcix(xics_phys + XICS_XIRR);
-       }
+       if (rc < 0)
+               return 1;
 
        /*
         * Save XIRR for later. Since we get control in reverse endian
@@ -445,15 +452,19 @@ static long kvmppc_read_one_intr(bool *again)
         * If it is an IPI, clear the MFRR and EOI it.
         */
        if (xisr == XICS_IPI) {
-               if (xics_phys) {
+               rc = 0;
+               if (!in_realmode()) {
+                       opal_int_set_mfrr(hard_smp_processor_id(), 0xff);
+                       rc = opal_int_eoi(h_xirr);
+               } else if (xics_phys) {
                        _stbcix(xics_phys + XICS_MFRR, 0xff);
                        _stwcix(xics_phys + XICS_XIRR, xirr);
                } else {
                        opal_rm_int_set_mfrr(hard_smp_processor_id(), 0xff);
                        rc = opal_rm_int_eoi(h_xirr);
-                       /* If rc > 0, there is another interrupt pending */
-                       *again = rc > 0;
                }
+               /* If rc > 0, there is another interrupt pending */
+               *again = rc > 0;
 
                /*
                 * Need to ensure side effects of above stores
@@ -471,7 +482,10 @@ static long kvmppc_read_one_intr(bool *again)
                        /* We raced with the host,
                         * we need to resend that IPI, bummer
                         */
-                       if (xics_phys)
+                       if (!in_realmode())
+                               opal_int_set_mfrr(hard_smp_processor_id(),
+                                                 IPI_PRIORITY);
+                       else if (xics_phys)
                                _stbcix(xics_phys + XICS_MFRR, IPI_PRIORITY);
                        else
                                opal_rm_int_set_mfrr(hard_smp_processor_id(),

diff --git a/arch/powerpc/kvm/book3s_hv_rm_xics.c b/arch/powerpc/kvm/book3s_hv_rm_xics.c
index 30f82c79de5ddfeea4bc2c4c96535efda0c1a4a3..de7b1e22a78d37e5e950f5100b815cce9d0f2059 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv_rm_xics.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_xics.c
@@ -72,11 +72,9 @@ static inline void icp_send_hcore_msg(int hcore, struct kvm_vcpu *vcpu)
        hcpu = hcore << threads_shift;
        kvmppc_host_rm_ops_hv->rm_core[hcore].rm_data = vcpu;
        smp_muxed_ipi_set_message(hcpu, PPC_MSG_RM_HOST_ACTION);
-       if (paca[hcpu].kvm_hstate.xics_phys)
-               icp_native_cause_ipi_rm(hcpu);
-       else
-               opal_rm_int_set_mfrr(get_hard_smp_processor_id(hcpu),
-                                    IPI_PRIORITY);
+       kvmppc_set_host_ipi(hcpu, 1);
+       smp_mb();
+       kvmhv_rm_send_ipi(hcpu);
 }
 #else
 static inline void icp_send_hcore_msg(int hcore, struct kvm_vcpu *vcpu) { }

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index dcc67a87d68818ee51be90ae5aae604bec8f5c49..46c1c1fe55c887fd0416c95514fca3af74501415 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -148,6 +148,15 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
        addi    r1, r1, 112
        ld      r7, HSTATE_HOST_MSR(r13)
 
+       /*
+        * If we came back from the guest via a relocation-on interrupt,
+        * we will be in virtual mode at this point, which makes it a
+        * little easier to get back to the caller.
+        */
+       mfmsr   r0
+       andi.   r0, r0, MSR_IR          /* in real mode? */
+       bne     .Lvirt_return
+
        cmpwi   cr1, r12, BOOK3S_INTERRUPT_MACHINE_CHECK
        cmpwi   r12, BOOK3S_INTERRUPT_EXTERNAL
        beq     11f
@@ -181,6 +190,26 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
        mtspr SPRN_HSRR1, r7
        ba    0xe80
 
+       /* Virtual-mode return - can't get here for HMI or machine check */
+.Lvirt_return:
+       cmpwi   r12, BOOK3S_INTERRUPT_EXTERNAL
+       beq     16f
+       cmpwi   r12, BOOK3S_INTERRUPT_H_DOORBELL
+       beq     17f
+       andi.   r0, r7, MSR_EE          /* were interrupts hard-enabled? */
+       beq     18f
+       mtmsrd  r7, 1                   /* if so then re-enable them */
+18:    mtlr    r8
+       blr
+
+16:    mtspr   SPRN_HSRR0, r8          /* jump to reloc-on external vector */
+       mtspr   SPRN_HSRR1, r7
+       b       exc_virt_0x4500_hardware_interrupt
+
+17:    mtspr   SPRN_HSRR0, r8
+       mtspr   SPRN_HSRR1, r7
+       b       exc_virt_0x4e80_h_doorbell
+
 kvmppc_primary_no_guest:
        /* We handle this much like a ceded vcpu */
        /* put the HDEC into the DEC, since HDEC interrupts don't wake us */