KVM: Allow cross page reads and writes from cached translations.

This patch adds support for kvm_gfn_to_hva_cache_init functions for reads and writes that will cross a page. If the range falls within the same memslot, then this will be a fast operation. If the range is split between two memslots, then the slower kvm_read_guest and kvm_write_guest are used. Tested: Test against kvm_clock unit tests.

Andrew Honig committed 13 years ago

Commit 8f964521 parent 09a6e1f5 files · +46 −19Browse files

Unified · Split

5 files

arch/x86/kvm/lapic.c +1 −1
arch/x86/kvm/x86.c +6 −7
include/linux/kvm_host.h +1 −1
include/linux/kvm_types.h +1 −0
virt/kvm/kvm_main.c +37 −10

arch/x86/kvm/lapic.c+1−1

@@ -1857,7 +1857,7 @@ int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data) · 1856 unmodified lines
1857	1857	if (!pv_eoi_enabled(vcpu))
1858	1858	return 0;
1859	1859	return kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.pv_eoi.data,
1860		− addr);
	1860	+ addr, sizeof(u8));
1861	1861	}
1862	1862
1863	1863	void kvm_lapic_init(void)

arch/x86/kvm/x86.c+6−7

@@ -1823,7 +1823,8 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data) · 1822 unmodified lines
1823	1823	return 0;
1824	1824	}
1825	1825
1826		− if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.apf.data, gpa))
	1826	+ if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.apf.data, gpa,
	1827	+ sizeof(u32)))
1827	1828	return 1;
1828	1829
1829	1830	vcpu->arch.apf.send_user_only = !(data & KVM_ASYNC_PF_SEND_ALWAYS);
@@ -1952,12 +1953,9 @@ int kvm_set_msr_common(struct kvm_vcpu vcpu, struct msr_data msr_info) · 122 unmodified lines
1952	1953
1953	1954	gpa_offset = data & ~(PAGE_MASK \| 1);
1954	1955
1955		− /* Check that the address is 32-byte aligned. */
1956		− if (gpa_offset & (sizeof(struct pvclock_vcpu_time_info) - 1))
1957		− break;
1958		−
1959	1956	if (kvm_gfn_to_hva_cache_init(vcpu->kvm,
1960		− &vcpu->arch.pv_time, data & ~1ULL))
	1957	+ &vcpu->arch.pv_time, data & ~1ULL,
	1958	+ sizeof(struct pvclock_vcpu_time_info)))
1961	1959	vcpu->arch.pv_time_enabled = false;
1962	1960	else
1963	1961	vcpu->arch.pv_time_enabled = true;
@@ -1977,7 +1975,8 @@ int kvm_set_msr_common(struct kvm_vcpu vcpu, struct msr_data msr_info) · 13 unmodified lines
1977	1975	return 1;
1978	1976
1979	1977	if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.st.stime,
1980		− data & KVM_STEAL_VALID_BITS))
	1978	+ data & KVM_STEAL_VALID_BITS,
	1979	+ sizeof(struct kvm_steal_time)))
1981	1980	return 1;
1982	1981
1983	1982	vcpu->arch.st.msr_val = data;

include/linux/kvm_host.h+1−1

@@ -518,7 +518,7 @@ int kvm_write_guest(struct kvm kvm, gpa_t gpa, const void data, · 517 unmodified lines
518	518	int kvm_write_guest_cached(struct kvm kvm, struct gfn_to_hva_cache ghc,
519	519	void *data, unsigned long len);
520	520	int kvm_gfn_to_hva_cache_init(struct kvm kvm, struct gfn_to_hva_cache ghc,
521		− gpa_t gpa);
	521	+ gpa_t gpa, unsigned long len);
522	522	int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len);
523	523	int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len);
524	524	struct kvm_memory_slot gfn_to_memslot(struct kvm kvm, gfn_t gfn);

include/linux/kvm_types.h+1−0

@@ -71,6 +71,7 @@ struct gfn_to_hva_cache { · 70 unmodified lines
71	71	u64 generation;
72	72	gpa_t gpa;
73	73	unsigned long hva;
	74	+ unsigned long len;
74	75	struct kvm_memory_slot *memslot;
75	76	};
76	77

virt/kvm/kvm_main.c+37−10

@@ -1541,21 +1541,38 @@ int kvm_write_guest(struct kvm kvm, gpa_t gpa, const void data, · 1540 unmodified lines
1541	1541	}
1542	1542
1543	1543	int kvm_gfn_to_hva_cache_init(struct kvm kvm, struct gfn_to_hva_cache ghc,
1544		− gpa_t gpa)
	1544	+ gpa_t gpa, unsigned long len)
1545	1545	{
1546	1546	struct kvm_memslots *slots = kvm_memslots(kvm);
1547	1547	int offset = offset_in_page(gpa);
1548		− gfn_t gfn = gpa >> PAGE_SHIFT;
	1548	+ gfn_t start_gfn = gpa >> PAGE_SHIFT;
	1549	+ gfn_t end_gfn = (gpa + len - 1) >> PAGE_SHIFT;
	1550	+ gfn_t nr_pages_needed = end_gfn - start_gfn + 1;
	1551	+ gfn_t nr_pages_avail;
1549	1552
1550	1553	ghc->gpa = gpa;
1551	1554	ghc->generation = slots->generation;
1552		− ghc->memslot = gfn_to_memslot(kvm, gfn);
1553		− ghc->hva = gfn_to_hva_many(ghc->memslot, gfn, NULL);
1554		− if (!kvm_is_error_hva(ghc->hva))
	1555	+ ghc->len = len;
	1556	+ ghc->memslot = gfn_to_memslot(kvm, start_gfn);
	1557	+ ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn, &nr_pages_avail);
	1558	+ if (!kvm_is_error_hva(ghc->hva) && nr_pages_avail >= nr_pages_needed) {
1555	1559	ghc->hva += offset;
1556		− else
1557		− return -EFAULT;
1558		−
	1560	+ } else {
	1561	+ /*
	1562	+ * If the requested region crosses two memslots, we still
	1563	+ * verify that the entire region is valid here.
	1564	+ */
	1565	+ while (start_gfn <= end_gfn) {
	1566	+ ghc->memslot = gfn_to_memslot(kvm, start_gfn);
	1567	+ ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn,
	1568	+ &nr_pages_avail);
	1569	+ if (kvm_is_error_hva(ghc->hva))
	1570	+ return -EFAULT;
	1571	+ start_gfn += nr_pages_avail;
	1572	+ }
	1573	+ /* Use the slow path for cross page reads and writes. */
	1574	+ ghc->memslot = NULL;
	1575	+ }
1559	1576	return 0;
1560	1577	}
1561	1578	EXPORT_SYMBOL_GPL(kvm_gfn_to_hva_cache_init);
@@ -1566,8 +1583,13 @@ int kvm_write_guest_cached(struct kvm kvm, struct gfn_to_hva_cache ghc, · 4 unmodified lines
1566	1583	struct kvm_memslots *slots = kvm_memslots(kvm);
1567	1584	int r;
1568	1585
	1586	+ BUG_ON(len > ghc->len);
	1587	+
1569	1588	if (slots->generation != ghc->generation)
1570		− kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa);
	1589	+ kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa, ghc->len);
	1590	+
	1591	+ if (unlikely(!ghc->memslot))
	1592	+ return kvm_write_guest(kvm, ghc->gpa, data, len);
1571	1593
1572	1594	if (kvm_is_error_hva(ghc->hva))
1573	1595	return -EFAULT;
@@ -1587,8 +1609,13 @@ int kvm_read_guest_cached(struct kvm kvm, struct gfn_to_hva_cache ghc, · 13 unmodified lines
1587	1609	struct kvm_memslots *slots = kvm_memslots(kvm);
1588	1610	int r;
1589	1611
	1612	+ BUG_ON(len > ghc->len);
	1613	+
1590	1614	if (slots->generation != ghc->generation)
1591		− kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa);
	1615	+ kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa, ghc->len);
	1616	+
	1617	+ if (unlikely(!ghc->memslot))
	1618	+ return kvm_read_guest(kvm, ghc->gpa, data, len);
1592	1619
1593	1620	if (kvm_is_error_hva(ghc->hva))
1594	1621	return -EFAULT;