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x86: KVM guest: hypercall based pte updates and TLB flushes

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Hypercall based pte updates are faster than faults, and also allow use
of the lazy MMU mode to batch operations.

Don't report the feature if two dimensional paging is enabled.

[avi:
 - guest/host split
 - fix 32-bit truncation issues
 - adjust to mmu_op
 - adjust to ->release_*() renamed
 - add ->release_pud()]

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Marcelo Tosatti 2008-02-22 12:21:37 -05:00 committed by Avi Kivity
parent 2f333bcb4e
commit 1da8a77bdc
1 changed files with 138 additions and 0 deletions
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138
arch/x86/kernel/kvm.c
View File

@ -25,6 +25,7 @@
#include <linux/kvm_para.h>
#include <linux/cpu.h>
#include <linux/mm.h>
#include <linux/highmem.h>
/*
* No need for any "IO delay" on KVM
@ -33,6 +34,122 @@ static void kvm_io_delay(void)
{
}
static void kvm_mmu_op(void *buffer, unsigned len)
{
int r;
unsigned long a1, a2;
do {
a1 = __pa(buffer);
a2 = 0; /* on i386 __pa() always returns <4G */
r = kvm_hypercall3(KVM_HC_MMU_OP, len, a1, a2);
buffer += r;
len -= r;
} while (len);
}
static void kvm_mmu_write(void *dest, u64 val)
{
__u64 pte_phys;
struct kvm_mmu_op_write_pte wpte;
#ifdef CONFIG_HIGHPTE
struct page *page;
unsigned long dst = (unsigned long) dest;
page = kmap_atomic_to_page(dest);
pte_phys = page_to_pfn(page);
pte_phys <<= PAGE_SHIFT;
pte_phys += (dst & ~(PAGE_MASK));
#else
pte_phys = (unsigned long)__pa(dest);
#endif
wpte.header.op = KVM_MMU_OP_WRITE_PTE;
wpte.pte_val = val;
wpte.pte_phys = pte_phys;
kvm_mmu_op(&wpte, sizeof wpte);
}
/*
* We only need to hook operations that are MMU writes. We hook these so that
* we can use lazy MMU mode to batch these operations. We could probably
* improve the performance of the host code if we used some of the information
* here to simplify processing of batched writes.
*/
static void kvm_set_pte(pte_t *ptep, pte_t pte)
{
kvm_mmu_write(ptep, pte_val(pte));
}
static void kvm_set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
kvm_mmu_write(ptep, pte_val(pte));
}
static void kvm_set_pmd(pmd_t *pmdp, pmd_t pmd)
{
kvm_mmu_write(pmdp, pmd_val(pmd));
}
#if PAGETABLE_LEVELS >= 3
#ifdef CONFIG_X86_PAE
static void kvm_set_pte_atomic(pte_t *ptep, pte_t pte)
{
kvm_mmu_write(ptep, pte_val(pte));
}
static void kvm_set_pte_present(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
kvm_mmu_write(ptep, pte_val(pte));
}
static void kvm_pte_clear(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
kvm_mmu_write(ptep, 0);
}
static void kvm_pmd_clear(pmd_t *pmdp)
{
kvm_mmu_write(pmdp, 0);
}
#endif
static void kvm_set_pud(pud_t *pudp, pud_t pud)
{
kvm_mmu_write(pudp, pud_val(pud));
}
#if PAGETABLE_LEVELS == 4
static void kvm_set_pgd(pgd_t *pgdp, pgd_t pgd)
{
kvm_mmu_write(pgdp, pgd_val(pgd));
}
#endif
#endif /* PAGETABLE_LEVELS >= 3 */
static void kvm_flush_tlb(void)
{
struct kvm_mmu_op_flush_tlb ftlb = {
.header.op = KVM_MMU_OP_FLUSH_TLB,
};
kvm_mmu_op(&ftlb, sizeof ftlb);
}
static void kvm_release_pt(u32 pfn)
{
struct kvm_mmu_op_release_pt rpt = {
.header.op = KVM_MMU_OP_RELEASE_PT,
.pt_phys = (u64)pfn << PAGE_SHIFT,
};
kvm_mmu_op(&rpt, sizeof rpt);
}
static void paravirt_ops_setup(void)
{
pv_info.name = "KVM";
@ -41,6 +158,27 @@ static void paravirt_ops_setup(void)
if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
pv_cpu_ops.io_delay = kvm_io_delay;
if (kvm_para_has_feature(KVM_FEATURE_MMU_OP)) {
pv_mmu_ops.set_pte = kvm_set_pte;
pv_mmu_ops.set_pte_at = kvm_set_pte_at;
pv_mmu_ops.set_pmd = kvm_set_pmd;
#if PAGETABLE_LEVELS >= 3
#ifdef CONFIG_X86_PAE
pv_mmu_ops.set_pte_atomic = kvm_set_pte_atomic;
pv_mmu_ops.set_pte_present = kvm_set_pte_present;
pv_mmu_ops.pte_clear = kvm_pte_clear;
pv_mmu_ops.pmd_clear = kvm_pmd_clear;
#endif
pv_mmu_ops.set_pud = kvm_set_pud;
#if PAGETABLE_LEVELS == 4
pv_mmu_ops.set_pgd = kvm_set_pgd;
#endif
#endif
pv_mmu_ops.flush_tlb_user = kvm_flush_tlb;
pv_mmu_ops.release_pte = kvm_release_pt;
pv_mmu_ops.release_pmd = kvm_release_pt;
pv_mmu_ops.release_pud = kvm_release_pt;
}
}
void __init kvm_guest_init(void)