[RFC PATCH 69/73] x86/pvm: Implement mmu related PVOPS

Lai Jiangshan
2024-02-26T14:39:43Z

CR2 is passed directly in the event entry, allowing it to be read
directly in PVOPS. Additionally, write_cr3() for context switch needs to
notify the hypervisor in its PVOPS. For performance reasons, TLB-related
PVOPS utilize hypercalls.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
---
arch/x86/kernel/pvm.c | 56 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 56 insertions(+)

diff --git a/arch/x86/kernel/pvm.c b/arch/x86/kernel/pvm.c
index b4522947374d..1dc2c0fb7daa 100644
--- a/arch/x86/kernel/pvm.c
+++ b/arch/x86/kernel/pvm.c
@@ -21,6 +21,7 @@
#include <asm/traps.h>

DEFINE_PER_CPU_PAGE_ALIGNED(struct pvm_vcpu_struct, pvm_vcpu_struct);
+static DEFINE_PER_CPU(unsigned long, pvm_guest_cr3);

unsigned long pvm_range_start __initdata;
unsigned long pvm_range_end __initdata;
@@ -153,6 +154,52 @@ static noinstr void pvm_safe_halt(void)
pvm_hypercall0(PVM_HC_IRQ_HALT);
}

+static noinstr unsigned long pvm_read_cr2(void)
+{
+ return this_cpu_read(pvm_vcpu_struct.cr2);
+}
+
+static noinstr void pvm_write_cr2(unsigned long cr2)
+{
+ native_write_cr2(cr2);
+ this_cpu_write(pvm_vcpu_struct.cr2, cr2);
+}
+
+static unsigned long pvm_read_cr3(void)
+{
+ return this_cpu_read(pvm_guest_cr3);
+}
+
+static unsigned long pvm_user_pgd(unsigned long pgd)
+{
+ return pgd | BIT(PTI_PGTABLE_SWITCH_BIT) | BIT(X86_CR3_PTI_PCID_USER_BIT);
+}
+
+static void pvm_write_cr3(unsigned long val)
+{
+ /* Convert CR3_NO_FLUSH bit to hypercall flags. */
+ unsigned long flags = ~val >> 63;
+ unsigned long pgd = val & ~X86_CR3_PCID_NOFLUSH;
+
+ this_cpu_write(pvm_guest_cr3, pgd);
+ pvm_hypercall3(PVM_HC_LOAD_PGTBL, flags, pgd, pvm_user_pgd(pgd));
+}
+
+static void pvm_flush_tlb_user(void)
+{
+ pvm_hypercall0(PVM_HC_TLB_FLUSH_CURRENT);
+}
+
+static void pvm_flush_tlb_kernel(void)
+{
+ pvm_hypercall0(PVM_HC_TLB_FLUSH);
+}
+
+static void pvm_flush_tlb_one_user(unsigned long addr)
+{
+ pvm_hypercall1(PVM_HC_TLB_INVLPG, addr);
+}
+
void __init pvm_early_event(struct pt_regs *regs)
{
int vector = regs->orig_ax >> 32;
@@ -397,6 +444,15 @@ void __init pvm_early_setup(void)
pv_ops.irq.irq_enable = __PV_IS_CALLEE_SAVE(pvm_irq_enable);
pv_ops.irq.safe_halt = pvm_safe_halt;

+ this_cpu_write(pvm_guest_cr3, __native_read_cr3());
+ pv_ops.mmu.read_cr2 = __PV_IS_CALLEE_SAVE(pvm_read_cr2);
+ pv_ops.mmu.write_cr2 = pvm_write_cr2;
+ pv_ops.mmu.read_cr3 = pvm_read_cr3;
+ pv_ops.mmu.write_cr3 = pvm_write_cr3;
+ pv_ops.mmu.flush_tlb_user = pvm_flush_tlb_user;
+ pv_ops.mmu.flush_tlb_kernel = pvm_flush_tlb_kernel;
+ pv_ops.mmu.flush_tlb_one_user = pvm_flush_tlb_one_user;
+
wrmsrl(MSR_PVM_VCPU_STRUCT, __pa(this_cpu_ptr(&pvm_vcpu_struct)));
wrmsrl(MSR_PVM_EVENT_ENTRY, (unsigned long)(void *)pvm_early_kernel_event_entry - 256);
wrmsrl(MSR_PVM_SUPERVISOR_REDZONE, PVM_SUPERVISOR_REDZONE_SIZE);
--
2.19.1.6.gb485710b