Re: [kvm-devel] [PATCH 7/8] MMU: add TDP support to the KVM MMU

From: Izik Eidus
Date: Thu Feb 07 2008 - 08:27:37 EST


Joerg Roedel wrote:
This patch contains the changes to the KVM MMU necessary for support of the
Nested Paging feature in AMD Barcelona and Phenom Processors.

good patch, it look like things will be very fixable with it

Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
---
arch/x86/kvm/mmu.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++--
arch/x86/kvm/mmu.h | 6 ++++
2 files changed, 82 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 5e76963..5304d55 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1081,6 +1081,7 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
int i;
gfn_t root_gfn;
struct kvm_mmu_page *sp;
+ int metaphysical = 0;
root_gfn = vcpu->arch.cr3 >> PAGE_SHIFT;
@@ -1089,14 +1090,20 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
hpa_t root = vcpu->arch.mmu.root_hpa;
ASSERT(!VALID_PAGE(root));
+ if (tdp_enabled)
+ metaphysical = 1;
sp = kvm_mmu_get_page(vcpu, root_gfn, 0,
- PT64_ROOT_LEVEL, 0, ACC_ALL, NULL, NULL);
+ PT64_ROOT_LEVEL, metaphysical,
+ ACC_ALL, NULL, NULL);
root = __pa(sp->spt);
++sp->root_count;
vcpu->arch.mmu.root_hpa = root;
return;
}
#endif
+ metaphysical = !is_paging(vcpu);
+ if (tdp_enabled)
+ metaphysical = 1;
for (i = 0; i < 4; ++i) {
hpa_t root = vcpu->arch.mmu.pae_root[i];
@@ -1110,7 +1117,7 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
} else if (vcpu->arch.mmu.root_level == 0)
root_gfn = 0;
sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
- PT32_ROOT_LEVEL, !is_paging(vcpu),
+ PT32_ROOT_LEVEL, metaphysical,
ACC_ALL, NULL, NULL);
root = __pa(sp->spt);
++sp->root_count;
@@ -1144,6 +1151,36 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
error_code & PFERR_WRITE_MASK, gfn);
}
+static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa,
+ u32 error_code)

you probably mean gpa_t ?

+{
+ struct page *page;
+ int r;
+
+ ASSERT(vcpu);
+ ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa));
+
+ r = mmu_topup_memory_caches(vcpu);
+ if (r)
+ return r;
+
+ down_read(&current->mm->mmap_sem);
+ page = gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT);
+ if (is_error_page(page)) {
+ kvm_release_page_clean(page);
+ up_read(&current->mm->mmap_sem);
+ return 1;
+ }

i dont know if it worth checking it here,
in the worth case we will map the error page and the host will be safe

+ spin_lock(&vcpu->kvm->mmu_lock);
+ kvm_mmu_free_some_pages(vcpu);
+ r = __direct_map(vcpu, gpa, error_code & PFERR_WRITE_MASK,
+ gpa >> PAGE_SHIFT, page, TDP_ROOT_LEVEL);
+ spin_unlock(&vcpu->kvm->mmu_lock);
+ up_read(&current->mm->mmap_sem);
+
+ return r;
+}
+
static void nonpaging_free(struct kvm_vcpu *vcpu)
{
mmu_free_roots(vcpu);
@@ -1237,7 +1274,35 @@ static int paging32E_init_context(struct kvm_vcpu *vcpu)
return paging64_init_context_common(vcpu, PT32E_ROOT_LEVEL);
}
-static int init_kvm_mmu(struct kvm_vcpu *vcpu)
tdp_page_fault(struct
+static int init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
+{
+ struct kvm_mmu *context = &vcpu->arch.mmu;
+
+ context->new_cr3 = nonpaging_new_cr3;
+ context->page_fault = tdp_page_fault;
+ context->free = nonpaging_free;
+ context->prefetch_page = nonpaging_prefetch_page;
+ context->shadow_root_level = TDP_ROOT_LEVEL;
+ context->root_hpa = INVALID_PAGE;
+
+ if (!is_paging(vcpu)) {
+ context->gva_to_gpa = nonpaging_gva_to_gpa;
+ context->root_level = 0;
+ } else if (is_long_mode(vcpu)) {
+ context->gva_to_gpa = paging64_gva_to_gpa;
+ context->root_level = PT64_ROOT_LEVEL;
+ } else if (is_pae(vcpu)) {
+ context->gva_to_gpa = paging64_gva_to_gpa;
+ context->root_level = PT32E_ROOT_LEVEL;
+ } else {
+ context->gva_to_gpa = paging32_gva_to_gpa;
+ context->root_level = PT32_ROOT_LEVEL;
+ }
+
+ return 0;
+}
+
+static int init_kvm_softmmu(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
@@ -1252,6 +1317,14 @@ static int init_kvm_mmu(struct kvm_vcpu *vcpu)
return paging32_init_context(vcpu);
}
+static int init_kvm_mmu(struct kvm_vcpu *vcpu)
+{
+ if (tdp_enabled)
+ return init_kvm_tdp_mmu(vcpu);
+ else
+ return init_kvm_softmmu(vcpu);
+}
+
static void destroy_kvm_mmu(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 1fce19e..e64e9f5 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -3,6 +3,12 @@
#include <linux/kvm_host.h>
+#ifdef CONFIG_X86_64
+#define TDP_ROOT_LEVEL PT64_ROOT_LEVEL
+#else
+#define TDP_ROOT_LEVEL PT32E_ROOT_LEVEL
+#endif
+
static inline void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
{
if (unlikely(vcpu->kvm->arch.n_free_mmu_pages < KVM_MIN_FREE_MMU_PAGES))


--
woof.

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