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KVM: MIPS: Support NetLogic KScratch registers

Browse source 
tlbex.c uses the implementation dependent $22 CP0 register group on
NetLogic cores, with the help of the c0_kscratch() helper. Allow these
registers to be allocated by the KVM entry code too instead of assuming
KScratch registers are all $31, which will also allow pgd_reg to be
handled since it is allocated that way.

We also drop the masking of kscratch_mask with 0xfc, as it is redundant
for the standard KScratch registers (Config4.KScrExist won't have the
low 2 bits set anyway), and apparently not necessary for NetLogic.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
This commit is contained in:
James Hogan 2016-11-11 14:08:32 +00:00
parent 7faa6eec69
commit 29b500b54e
1 changed files with 20 additions and 5 deletions
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25
arch/mips/kvm/entry.c
View file

@ -91,6 +91,21 @@ static void *kvm_mips_build_ret_from_exit(void *addr);
static void *kvm_mips_build_ret_to_guest(void *addr);
static void *kvm_mips_build_ret_to_host(void *addr);
/*
* The version of this function in tlbex.c uses current_cpu_type(), but for KVM
* we assume symmetry.
*/
static int c0_kscratch(void)
{
switch (boot_cpu_type()) {
case CPU_XLP:
case CPU_XLR:
return 22;
default:
return 31;
}
}
/**
* kvm_mips_entry_setup() - Perform global setup for entry code.
*
@ -105,18 +120,18 @@ int kvm_mips_entry_setup(void)
* We prefer to use KScratchN registers if they are available over the
* defaults above, which may not work on all cores.
*/
unsigned int kscratch_mask = cpu_data[0].kscratch_mask & 0xfc;
unsigned int kscratch_mask = cpu_data[0].kscratch_mask;
/* Pick a scratch register for storing VCPU */
if (kscratch_mask) {
scratch_vcpu[0] = 31;
scratch_vcpu[0] = c0_kscratch();
scratch_vcpu[1] = ffs(kscratch_mask) - 1;
kscratch_mask &= ~BIT(scratch_vcpu[1]);
}
/* Pick a scratch register to use as a temp for saving state */
if (kscratch_mask) {
scratch_tmp[0] = 31;
scratch_tmp[0] = c0_kscratch();
scratch_tmp[1] = ffs(kscratch_mask) - 1;
kscratch_mask &= ~BIT(scratch_tmp[1]);
}
@ -132,7 +147,7 @@ static void kvm_mips_build_save_scratch(u32 **p, unsigned int tmp,
UASM_i_SW(p, tmp, offsetof(struct pt_regs, cp0_epc), frame);
/* Save the temp scratch register value in cp0_cause of stack frame */
if (scratch_tmp[0] == 31) {
if (scratch_tmp[0] == c0_kscratch()) {
UASM_i_MFC0(p, tmp, scratch_tmp[0], scratch_tmp[1]);
UASM_i_SW(p, tmp, offsetof(struct pt_regs, cp0_cause), frame);
}
@ -148,7 +163,7 @@ static void kvm_mips_build_restore_scratch(u32 **p, unsigned int tmp,
UASM_i_LW(p, tmp, offsetof(struct pt_regs, cp0_epc), frame);
UASM_i_MTC0(p, tmp, scratch_vcpu[0], scratch_vcpu[1]);
if (scratch_tmp[0] == 31) {
if (scratch_tmp[0] == c0_kscratch()) {
UASM_i_LW(p, tmp, offsetof(struct pt_regs, cp0_cause), frame);
UASM_i_MTC0(p, tmp, scratch_tmp[0], scratch_tmp[1]);
}